icalendar.cal package#

Calendar is a dictionary like Python object that can render itself as VCAL files according to RFC 5545.

These are the defined components.

class icalendar.cal.Alarm(*args, **kwargs)[source]#

Bases: Component

A “VALARM” calendar component is a grouping of component properties that defines an alarm or reminder for an event or a to-do. For example, it may be used to define a reminder for a pending event or an overdue to-do.

property ACKNOWLEDGED: datetime | None#

The ACKNOWLEDGED property. datetime in UTC

All values will be converted to a datetime in UTC. This is defined in RFC 9074:

Purpose: This property specifies the UTC date and time at which the corresponding alarm was last sent or acknowledged.

This property is used to specify when an alarm was last sent or acknowledged. This allows clients to determine when a pending alarm has been acknowledged by a calendar user so that any alerts can be dismissed across multiple devices. It also allows clients to track repeating alarms or alarms on recurring events or to-dos to ensure that the right number of missed alarms can be tracked.

Clients SHOULD set this property to the current date-time value in UTC when a calendar user acknowledges a pending alarm. Certain kinds of alarms, such as email-based alerts, might not provide feedback as to when the calendar user sees them. For those kinds of alarms, the client SHOULD set this property when the alarm is triggered and the action is successfully carried out.

When an alarm is triggered on a client, clients can check to see if an “ACKNOWLEDGED” property is present. If it is, and the value of that property is greater than or equal to the computed trigger time for the alarm, then the client SHOULD NOT trigger the alarm. Similarly, if an alarm has been triggered and an “alert” has been presented to a calendar user, clients can monitor the iCalendar data to determine whether an “ACKNOWLEDGED” property is added or changed in the alarm component. If the value of any “ACKNOWLEDGED” property in the alarm changes and is greater than or equal to the trigger time of the alarm, then clients SHOULD dismiss or cancel any “alert” presented to the calendar user.

property DURATION: timedelta | None#

The DURATION property of an alarm component.

The alarm can be defined such that it triggers repeatedly. A definition of an alarm with a repeating trigger MUST include both the “DURATION” and “REPEAT” properties. The “DURATION” property specifies the delay period, after which the alarm will repeat.

property REPEAT: int#

The REPEAT property of an alarm component.

The alarm can be defined such that it triggers repeatedly. A definition of an alarm with a repeating trigger MUST include both the “DURATION” and “REPEAT” properties. The “DURATION” property specifies the delay period, after which the alarm will repeat. The “REPEAT” property specifies the number of additional repetitions that the alarm will be triggered. This repetition count is in addition to the initial triggering of the alarm.

property TRIGGER: timedelta | datetime | None#

The TRIGGER property.

Purpose: This property specifies when an alarm will trigger.

Value Type: The default value type is DURATION. The value type can be set to a DATE-TIME value type, in which case the value MUST specify a UTC-formatted DATE-TIME value.

Either a positive or negative duration may be specified for the “TRIGGER” property. An alarm with a positive duration is triggered after the associated start or end of the event or to-do. An alarm with a negative duration is triggered before the associated start or end of the event or to-do.

Accepted values: datetime, timedelta. If the attribute has invalid values, we raise InvalidCalendar. If the value is absent, we return None. You can also delete the value with del or by setting it to None.

The RELATED parameter of the TRIGGER property.

Values are either “START” (default) or “END”.

A value of START will set the alarm to trigger off the start of the associated event or to-do. A value of END will set the alarm to trigger off the end of the associated event or to-do.

In this example, we create an alarm that triggers two hours after the end of its parent component:

>>> from icalendar import Alarm
>>> from datetime import timedelta
>>> alarm = Alarm()
>>> alarm.TRIGGER = timedelta(hours=2)
>>> alarm.TRIGGER_RELATED = "END"
class Triggers(start: tuple[timedelta], end: tuple[timedelta], absolute: tuple[datetime])[source]#

Bases: NamedTuple

The computed times of alarm triggers.

start - triggers relative to the start of the Event or Todo (timedelta)

end - triggers relative to the end of the Event or Todo (timedelta)

absolute - triggers at a datetime in UTC

absolute: tuple[datetime]#

Alias for field number 2

end: tuple[timedelta]#

Alias for field number 1

start: tuple[timedelta]#

Alias for field number 0

property attendees: list[vCalAddress]#

ATTENDEE defines one or more “Attendees” within a calendar component.

Conformance:

This property MUST be specified in an iCalendar object that specifies a group-scheduled calendar entity. This property MUST NOT be specified in an iCalendar object when publishing the calendar information (e.g., NOT in an iCalendar object that specifies the publication of a calendar user’s busy time, event, to-do, or journal). This property is not specified in an iCalendar object that specifies only a time zone definition or that defines calendar components that are not group-scheduled components, but are components only on a single user’s calendar.

Description:

This property MUST only be specified within calendar components to specify participants, non-participants, and the chair of a group-scheduled calendar entity. The property is specified within an “EMAIL” category of the “VALARM” calendar component to specify an email address that is to receive the email type of iCalendar alarm.

Examples

Add a new attendee to an existing event.

>>> from icalendar import Event, vCalAddress
>>> event = Event()
>>> event.attendees.append(vCalAddress("mailto:me@my-domain.com"))
>>> print(event.to_ical())
BEGIN:VEVENT
ATTENDEE:mailto:me@my-domain.com
END:VEVENT

Create an email alarm with several attendees:

>>> from icalendar import Alarm, vCalAddress
>>> alarm = Alarm.new(attendees = [
...     vCalAddress("mailto:me@my-domain.com"),
...     vCalAddress("mailto:you@my-domain.com"),
... ], summary = "Email alarm")
>>> print(alarm.to_ical())
BEGIN:VALARM
ATTENDEE:mailto:me@my-domain.com
ATTENDEE:mailto:you@my-domain.com
SUMMARY:Email alarm
END:VALARM
property description: str | None#

DESCRIPTION provides a more complete description of the calendar component than that provided by the “SUMMARY” property.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

The property can be specified in the “VEVENT”, “VTODO”, “VJOURNAL”, or “VALARM” calendar components. The property can be specified multiple times only within a “VJOURNAL” calendar component.

Description:

This property is used in the “VEVENT” and “VTODO” to capture lengthy textual descriptions associated with the activity.

This property is used in the “VALARM” calendar component to capture the display text for a DISPLAY category of alarm, and to capture the body text for an EMAIL category of alarm.

Examples

The following is an example of this property with formatted line breaks in the property value:

DESCRIPTION:Meeting to provide technical review for "Phoenix"
 design.\nHappy Face Conference Room. Phoenix design team
 MUST attend this meeting.\nRSVP to team leader.
inclusive: tuple[str] | tuple[tuple[str, str]] = (('DURATION', 'REPEAT'), ('SUMMARY', 'ATTENDEE'))#
multiple = ('ATTENDEE', 'ATTACH', 'RELATED-TO')#
name = 'VALARM'#
classmethod new(attendees: list[vCalAddress] | None = None, description: str | None = None, summary: str | None = None, uid: str | uuid.UUID | None = None)[source]#

Create a new alarm with all required properties.

This creates a new Alarm in accordance with RFC 5545.

Parameters:

  • attendees – The attendees of the alarm.

  • description – The description of the alarm.

  • summary – The summary of the alarm.

  • uid – The uid of the alarm.

Returns:

Alarm

Raises:

InvalidCalendar – If the content is not valid according to RFC 5545.

Warning

As time progresses, we will be stricter with the validation.

required = ('ACTION', 'TRIGGER')#
singletons = ('ATTACH', 'ACTION', 'DESCRIPTION', 'SUMMARY', 'TRIGGER', 'DURATION', 'REPEAT', 'UID', 'PROXIMITY', 'ACKNOWLEDGED')#
subcomponents: list[Component]#
property summary: str | None#

SUMMARY defines a short summary or subject for the calendar component.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

The property can be specified in “VEVENT”, “VTODO”, “VJOURNAL”, or “VALARM” calendar components.

Description:

This property is used in the “VEVENT”, “VTODO”, and “VJOURNAL” calendar components to capture a short, one-line summary about the activity or journal entry.

This property is used in the “VALARM” calendar component to capture the subject of an EMAIL category of alarm.

Examples

The following is an example of this property:

SUMMARY:Department Party
property triggers#

The computed triggers of an Alarm.

This takes the TRIGGER, DURATION and REPEAT properties into account.

Here, we create an alarm that triggers 3 times before the start of the parent component:

>>> from icalendar import Alarm
>>> from datetime import timedelta
>>> alarm = Alarm()
>>> alarm.TRIGGER = timedelta(hours=-4)  # trigger 4 hours before START
>>> alarm.DURATION = timedelta(hours=1)  # after 1 hour trigger again
>>> alarm.REPEAT = 2  # trigger 2 more times
>>> alarm.triggers.start == (timedelta(hours=-4),  timedelta(hours=-3),  timedelta(hours=-2))
True
>>> alarm.triggers.end
()
>>> alarm.triggers.absolute
()
property uid: str#

UID specifies the persistent, globally unique identifier for a component.

We recommend using uuid.uuid4() to generate new values.

Returns:

The value of the UID property as a string or "" if no value is set.

Description:

The “UID” itself MUST be a globally unique identifier. The generator of the identifier MUST guarantee that the identifier is unique.

This is the method for correlating scheduling messages with the referenced “VEVENT”, “VTODO”, or “VJOURNAL” calendar component. The full range of calendar components specified by a recurrence set is referenced by referring to just the “UID” property value corresponding to the calendar component. The “RECURRENCE-ID” property allows the reference to an individual instance within the recurrence set.

This property is an important method for group-scheduling applications to match requests with later replies, modifications, or deletion requests. Calendaring and scheduling applications MUST generate this property in “VEVENT”, “VTODO”, and “VJOURNAL” calendar components to assure interoperability with other group- scheduling applications. This identifier is created by the calendar system that generates an iCalendar object.

Implementations MUST be able to receive and persist values of at least 255 octets for this property, but they MUST NOT truncate values in the middle of a UTF-8 multi-octet sequence.

RFC 7986 states that UID can be used, for example, to identify duplicate calendar streams that a client may have been given access to. It can be used in conjunction with the “LAST-MODIFIED” property also specified on the “VCALENDAR” object to identify the most recent version of a calendar.

Conformance:

RFC 5545 states that the “UID” property can be specified on “VEVENT”, “VTODO”, and “VJOURNAL” calendar components. RFC 7986 modifies the definition of the “UID” property to allow it to be defined in an iCalendar object. RFC 9074 adds a “UID” property to “VALARM” components to allow a unique identifier to be specified. The value of this property can then be used to refer uniquely to the “VALARM” component.

This property can be specified once only.

Security:

RFC 7986 states that UID values MUST NOT include any data that might identify a user, host, domain, or any other security- or privacy-sensitive information. It is RECOMMENDED that calendar user agents now generate “UID” values that are hex-encoded random Universally Unique Identifier (UUID) values as defined in Sections 4.4 and 4.5 of RFC 4122. You can use the uuid module to generate new UUIDs.

Compatibility:

For Alarms, X-ALARMUID is also considered.

Examples

The following is an example of such a property value: 5FC53010-1267-4F8E-BC28-1D7AE55A7C99.

Set the UID of a calendar:

>>> from icalendar import Calendar
>>> from uuid import uuid4
>>> calendar = Calendar()
>>> calendar.uid = uuid4()
>>> print(calendar.to_ical())
BEGIN:VCALENDAR
UID:d755cef5-2311-46ed-a0e1-6733c9e15c63
END:VCALENDAR
class icalendar.cal.Availability(*args, **kwargs)[source]#

Bases: Component

VAVAILABILITY component from RFC 7953.

This provides a grouping of component properties and subcomponents that describe the availability associated with a calendar user.

Description:

A “VAVAILABILITY” component indicates a period of time within which availability information is provided. A “VAVAILABILITY” component can specify a start time and an end time or duration. If “DTSTART” is not present, then the start time is unbounded. If “DTEND” or “DURATION” are not present, then the end time is unbounded. Within the specified time period, availability defaults to a free-busy type of “BUSY-UNAVAILABLE” (see Section 3.2), except for any time periods corresponding to “AVAILABLE” subcomponents.

“AVAILABLE” subcomponents are used to indicate periods of free time within the time range of the enclosing “VAVAILABILITY” component. “AVAILABLE” subcomponents MAY include recurrence properties to specify recurring periods of time, which can be overridden using normal iCalendar recurrence behavior (i.e., use of the “RECURRENCE-ID” property).

If specified, the “DTSTART” and “DTEND” properties in “VAVAILABILITY” components and “AVAILABLE” subcomponents MUST be “DATE-TIME” values specified as either the date with UTC time or the date with local time and a time zone reference.

The iCalendar object containing the “VAVAILABILITY” component MUST contain appropriate “VTIMEZONE” components corresponding to each unique “TZID” parameter value used in any DATE-TIME properties in all components, unless [RFC7809] is in effect.

When used to publish available time, the “ORGANIZER” property specifies the calendar user associated with the published available time.

If the “PRIORITY” property is specified in “VAVAILABILITY” components, it is used to determine how that component is combined with other “VAVAILABILITY” components. See Section 4.

Other calendar properties MAY be specified in “VAVAILABILITY” or “AVAILABLE” components and are considered attributes of the marked block of time. Their usage is application specific. For example, the “LOCATION” property might be used to indicate that a person is available in one location for part of the week and a different location for another part of the week (but see Section 9 for when it is appropriate to add additional data like this).

Example

The following is an example of a “VAVAILABILITY” calendar component used to represent the availability of a user, always available Monday through Friday, 9:00 am to 5:00 pm in the America/Montreal time zone:

BEGIN:VAVAILABILITY
ORGANIZER:mailto:bernard@example.com
UID:0428C7D2-688E-4D2E-AC52-CD112E2469DF
DTSTAMP:20111005T133225Z
BEGIN:AVAILABLE
UID:34EDA59B-6BB1-4E94-A66C-64999089C0AF
SUMMARY:Monday to Friday from 9:00 to 17:00
DTSTART;TZID=America/Montreal:20111002T090000
DTEND;TZID=America/Montreal:20111002T170000
RRULE:FREQ=WEEKLY;BYDAY=MO,TU,WE,TH,FR
END:AVAILABLE
END:VAVAILABILITY

You can get the same example from example():

The following is an example of a “VAVAILABILITY” calendar component used to represent the availability of a user available Monday through Thursday, 9:00 am to 5:00 pm, at the main office, and Friday, 9:00 am to 12:00 pm, in the branch office in the America/Montreal time zone between October 2nd and December 2nd 2011:

BEGIN:VAVAILABILITY
ORGANIZER:mailto:bernard@example.com
UID:84D0F948-7FC6-4C1D-BBF3-BA9827B424B5
DTSTAMP:20111005T133225Z
DTSTART;TZID=America/Montreal:20111002T000000
DTEND;TZID=America/Montreal:20111202T000000
BEGIN:AVAILABLE
UID:7B33093A-7F98-4EED-B381-A5652530F04D
SUMMARY:Monday to Thursday from 9:00 to 17:00
DTSTART;TZID=America/Montreal:20111002T090000
DTEND;TZID=America/Montreal:20111002T170000
RRULE:FREQ=WEEKLY;BYDAY=MO,TU,WE,TH
LOCATION:Main Office
END:AVAILABLE
BEGIN:AVAILABLE
UID:DF39DC9E-D8C3-492F-9101-0434E8FC1896
SUMMARY:Friday from 9:00 to 12:00
DTSTART;TZID=America/Montreal:20111006T090000
DTEND;TZID=America/Montreal:20111006T120000
RRULE:FREQ=WEEKLY
LOCATION:Branch Office
END:AVAILABLE
END:VAVAILABILITY

For more examples, have a look at RFC 5545.

property DTEND: datetime | None#

The DTEND property. datetime in UTC

All values will be converted to a datetime in UTC. Start of the component.

This is almost the same as Event.DTEND with one exception: The values MUST have a timezone and DATE is not allowed.

Description:

RFC 7953: If specified, the “DTSTART” and “DTEND” properties in “VAVAILABILITY” components and “AVAILABLE” subcomponents MUST be “DATE-TIME” values specified as either the date with UTC time or the date with local time and a time zone reference.

property DTSTART: datetime | None#

The DTSTART property. datetime in UTC

All values will be converted to a datetime in UTC. Start of the component.

This is almost the same as Event.DTSTART with one exception: The values MUST have a timezone and DATE is not allowed.

Description:

RFC 7953: If specified, the “DTSTART” and “DTEND” properties in “VAVAILABILITY” components and “AVAILABLE” subcomponents MUST be “DATE-TIME” values specified as either the date with UTC time or the date with local time and a time zone reference.

property DURATION: timedelta | None#

The DURATION property.

The “DTSTART” property for a “Availability” specifies the inclusive start of the Availability. The “DURATION” property in conjunction with the DTSTART property for a “Availability” calendar component specifies the non-inclusive end of the event.

If you would like to calculate the duration of a Availability, do not use this. Instead use the duration property (lower case).

property available: list[Available]#

All VAVAILABLE sub-components.

This is a shortcut to get all VAVAILABLE sub-components. Modifications do not change the calendar. Use Component.add_component().

property busy_type: StrEnum#

BUSYTYPE specifies the default busy time type.

Returns:

icalendar.enums.BUSYTYPE

Description:

This property is used to specify the default busy time type. The values correspond to those used by the FBTYPE” parameter used on a “FREEBUSY” property, with the exception that the “FREE” value is not used in this property. If not specified on a component that allows this property, the default is “BUSY- UNAVAILABLE”.

canonical_order = ('DTSTART', 'DTEND', 'DURATION', 'DTSTAMP', 'UID', 'SEQUENCE', 'SUMMARY', 'DESCRIPTION', 'ORGANIZER')#
property categories: list[str]#

This property defines the categories for a component.

Property Parameters:

IANA, non-standard, and language property parameters can be specified on this property.

Conformance:

The property can be specified within “VEVENT”, “VTODO”, or “VJOURNAL” calendar components. Since RFC 7986 it can also be defined on a “VCALENDAR” component.

Description:

This property is used to specify categories or subtypes of the calendar component. The categories are useful in searching for a calendar component of a particular type and category. Within the “VEVENT”, “VTODO”, or “VJOURNAL” calendar components, more than one category can be specified as a COMMA-separated list of categories.

Example

Below, we add the categories to an event:

>>> from icalendar import Event
>>> event = Event()
>>> event.categories = ["Work", "Meeting"]
>>> print(event.to_ical())
BEGIN:VEVENT
CATEGORIES:Work,Meeting
END:VEVENT
>>> event.categories.append("Lecture")
>>> event.categories == ["Work", "Meeting", "Lecture"]
True

Note

At present, we do not take the LANGUAGE parameter into account.

property classification: StrEnum#

CLASS specifies the class of the calendar component.

Returns:

icalendar.enums.CLASS

Description:

An access classification is only one component of the general security system within a calendar application. It provides a method of capturing the scope of the access the calendar owner intends for information within an individual calendar entry. The access classification of an individual iCalendar component is useful when measured along with the other security components of a calendar system (e.g., calendar user authentication, authorization, access rights, access role, etc.). Hence, the semantics of the individual access classifications cannot be completely defined by this memo alone. Additionally, due to the “blind” nature of most exchange processes using this memo, these access classifications cannot serve as an enforcement statement for a system receiving an iCalendar object. Rather, they provide a method for capturing the intention of the calendar owner for the access to the calendar component. If not specified in a component that allows this property, the default value is PUBLIC. Applications MUST treat x-name and iana-token values they don’t recognize the same way as they would the PRIVATE value.

property contacts: list[str]#

Contact information associated with the calendar component.

Purpose:

This property is used to represent contact information or alternately a reference to contact information associated with the calendar component.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

In RFC 5545, this property can be specified in a “VEVENT”, “VTODO”, “VJOURNAL”, or “VFREEBUSY” calendar component. In RFC 7953, this property can be specified in a “VAVAILABILITY” amd “VAVAILABLE” calendar component.

Description:

The property value consists of textual contact information. An alternative representation for the property value can also be specified that refers to a URI pointing to an alternate form, such as a vCard RFC 2426, for the contact information.

Example

The following is an example of this property referencing textual contact information:

CONTACT:Jim Dolittle\, ABC Industries\, +1-919-555-1234

The following is an example of this property with an alternate representation of an LDAP URI to a directory entry containing the contact information:

CONTACT;ALTREP="ldap://example.com:6666/o=ABC%20Industries\,
c=US???(cn=Jim%20Dolittle)":Jim Dolittle\, ABC Industries\,
+1-919-555-1234

The following is an example of this property with an alternate representation of a MIME body part containing the contact information, such as a vCard RFC 2426 embedded in a text/ directory media type RFC 2425:

CONTACT;ALTREP="CID:part3.msg970930T083000SILVER@example.com":
 Jim Dolittle\, ABC Industries\, +1-919-555-1234

The following is an example of this property referencing a network resource, such as a vCard RFC 2426 object containing the contact information:

CONTACT;ALTREP="http://example.com/pdi/jdoe.vcf":Jim
 Dolittle\, ABC Industries\, +1-919-555-1234
property description: str | None#

DESCRIPTION provides a more complete description of the calendar component than that provided by the “SUMMARY” property.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

The property can be specified in the “VEVENT”, “VTODO”, “VJOURNAL”, or “VALARM” calendar components. The property can be specified multiple times only within a “VJOURNAL” calendar component.

Description:

This property is used in the “VEVENT” and “VTODO” to capture lengthy textual descriptions associated with the activity.

This property is used in the “VALARM” calendar component to capture the display text for a DISPLAY category of alarm, and to capture the body text for an EMAIL category of alarm.

Examples

The following is an example of this property with formatted line breaks in the property value:

DESCRIPTION:Meeting to provide technical review for "Phoenix"
 design.\nHappy Face Conference Room. Phoenix design team
 MUST attend this meeting.\nRSVP to team leader.
property duration: timedelta | None#

Compute the duration of this component.

If there is no DTEND or DURATION set, this is None. Otherwise, the duration is calculated from DTSTART and DTEND/DURATION.

This is in accordance with RFC 7953: If “DTEND” or “DURATION” are not present, then the end time is unbounded.

property end: timedelta | None#

Compute the duration of this component.

If there is no DTEND or DURATION set, this is None. Otherwise, the duration is calculated from DTSTART and DTEND/DURATION.

This is in accordance with RFC 7953: If “DTEND” or “DURATION” are not present, then the end time is unbounded.

classmethod example(name: str = 'rfc_7953_1') → Availability[source]#

Return the calendar example with the given name.

exclusive = ('DTEND', 'DURATION')#
property location: str | None#

The intended venue for the activity defined by a calendar component.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

Since RFC 5545, this property can be specified in “VEVENT” or “VTODO” calendar component. RFC 7953 adds this property to “VAVAILABILITY” and “VAVAILABLE”.

Description:

Specific venues such as conference or meeting rooms may be explicitly specified using this property. An alternate representation may be specified that is a URI that points to directory information with more structured specification of the location. For example, the alternate representation may specify either an LDAP URL RFC 4516 pointing to an LDAP server entry or a CID URL RFC 2392 pointing to a MIME body part containing a Virtual-Information Card (vCard) RFC 2426 for the location.

name = 'VAVAILABILITY'#
classmethod new(busy_type: BUSYTYPE | None = None, categories: Sequence[str] = (), comments: list[str] | str | None = None, components: Sequence[Available] | None = (), contacts: list[str] | str | None = None, created: date | None = None, classification: CLASS | None = None, description: str | None = None, end: datetime | None = None, last_modified: date | None = None, location: str | None = None, organizer: vCalAddress | str | None = None, priority: int | None = None, sequence: int | None = None, stamp: date | None = None, start: datetime | None = None, summary: str | None = None, uid: str | uuid.UUID | None = None, url: str | None = None)[source]#

Create a new event with all required properties.

This creates a new Availability in accordance with RFC 7953.

Parameters:
Returns:

Availability

Raises:

InvalidCalendar – If the content is not valid according to RFC 7953.

Warning

As time progresses, we will be stricter with the validation.

property organizer: vCalAddress | None#

ORGANIZER defines the organizer for a calendar component.

Property Parameters:

IANA, non-standard, language, common name, directory entry reference, and sent-by property parameters can be specified on this property.

Conformance:

This property MUST be specified in an iCalendar object that specifies a group-scheduled calendar entity. This property MUST be specified in an iCalendar object that specifies the publication of a calendar user’s busy time. This property MUST NOT be specified in an iCalendar object that specifies only a time zone definition or that defines calendar components that are not group-scheduled components, but are components only on a single user’s calendar.

Description:

This property is specified within the “VEVENT”, “VTODO”, and “VJOURNAL” calendar components to specify the organizer of a group-scheduled calendar entity. The property is specified within the “VFREEBUSY” calendar component to specify the calendar user requesting the free or busy time. When publishing a “VFREEBUSY” calendar component, the property is used to specify the calendar that the published busy time came from.

The property has the property parameters “CN”, for specifying the common or display name associated with the “Organizer”, “DIR”, for specifying a pointer to the directory information associated with the “Organizer”, “SENT-BY”, for specifying another calendar user that is acting on behalf of the “Organizer”. The non-standard parameters may also be specified on this property. If the “LANGUAGE” property parameter is specified, the identified language applies to the “CN” parameter value.

property priority: int#
Conformance:

This property can be specified in “VEVENT” and “VTODO” calendar components according to RFC 5545. RFC 7953 adds this property to “VAVAILABILITY”.

Description:

This priority is specified as an integer in the range 0 to 9. A value of 0 specifies an undefined priority. A value of 1 is the highest priority. A value of 2 is the second highest priority. Subsequent numbers specify a decreasing ordinal priority. A value of 9 is the lowest priority.

A CUA with a three-level priority scheme of “HIGH”, “MEDIUM”, and “LOW” is mapped into this property such that a property value in the range of 1 to 4 specifies “HIGH” priority. A value of 5 is the normal or “MEDIUM” priority. A value in the range of 6 to 9 is “LOW” priority.

A CUA with a priority schema of “A1”, “A2”, “A3”, “B1”, “B2”, …, “C3” is mapped into this property such that a property value of 1 specifies “A1”, a property value of 2 specifies “A2”, a property value of 3 specifies “A3”, and so forth up to a property value of 9 specifies “C3”.

Other integer values are reserved for future use.

Within a “VEVENT” calendar component, this property specifies a priority for the event. This property may be useful when more than one event is scheduled for a given time period.

Within a “VTODO” calendar component, this property specified a priority for the to-do. This property is useful in prioritizing multiple action items for a given time period.

required = ('DTSTART', 'DTSTAMP', 'UID')#
property sequence: int#

This property defines the revision sequence number of the calendar component within a sequence of revisions.

Value Type:

INTEGER

Property Parameters:

IANA and non-standard property parameters can be specified on this property.

Conformance:

The property can be specified in “VEVENT”, “VTODO”, or “VJOURNAL” calendar component.

Description:

When a calendar component is created, its sequence number is 0. It is monotonically incremented by the “Organizer’s” CUA each time the “Organizer” makes a significant revision to the calendar component.

The “Organizer” includes this property in an iCalendar object that it sends to an “Attendee” to specify the current version of the calendar component.

The “Attendee” includes this property in an iCalendar object that it sends to the “Organizer” to specify the version of the calendar component to which the “Attendee” is referring.

A change to the sequence number is not the mechanism that an “Organizer” uses to request a response from the “Attendees”. The “RSVP” parameter on the “ATTENDEE” property is used by the “Organizer” to indicate that a response from the “Attendees” is requested.

Recurrence instances of a recurring component MAY have different sequence numbers.

Examples

The following is an example of this property for a calendar component that was just created by the “Organizer”:

>>> from icalendar import Event
>>> event = Event()
>>> event.sequence
0

The following is an example of this property for a calendar component that has been revised 10 different times by the “Organizer”:

>>> from icalendar import Calendar
>>> calendar = Calendar.example("issue_156_RDATE_with_PERIOD_TZID_khal")
>>> event = calendar.events[0]
>>> event.sequence
10
singletons = ('DTSTAMP', 'UID', 'BUSYTYPE', 'CLASS', 'CREATED', 'DESCRIPTION', 'DTSTART', 'LAST-MODIFIED', 'LOCATION', 'ORGANIZER', 'PRIORITY', 'SEQUENCE', 'SUMMARY', 'URL', 'DTEND', 'DURATION')#
property start: datetime | None#

The DTSTART property. datetime in UTC

All values will be converted to a datetime in UTC. Start of the component.

This is almost the same as Event.DTSTART with one exception: The values MUST have a timezone and DATE is not allowed.

Description:

RFC 7953: If specified, the “DTSTART” and “DTEND” properties in “VAVAILABILITY” components and “AVAILABLE” subcomponents MUST be “DATE-TIME” values specified as either the date with UTC time or the date with local time and a time zone reference.

subcomponents: list[Component]#
property summary: str | None#

SUMMARY defines a short summary or subject for the calendar component.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

The property can be specified in “VEVENT”, “VTODO”, “VJOURNAL”, or “VALARM” calendar components.

Description:

This property is used in the “VEVENT”, “VTODO”, and “VJOURNAL” calendar components to capture a short, one-line summary about the activity or journal entry.

This property is used in the “VALARM” calendar component to capture the subject of an EMAIL category of alarm.

Examples

The following is an example of this property:

SUMMARY:Department Party
property url: str#

A Uniform Resource Locator (URL) associated with the iCalendar object.

Description:

This property may be used in a calendar component to convey a location where a more dynamic rendition of the calendar information associated with the calendar component can be found. This memo does not attempt to standardize the form of the URI, nor the format of the resource pointed to by the property value. If the URL property and Content-Location MIME header are both specified, they MUST point to the same resource.

Conformance:

This property can be specified once in the “VEVENT”, “VTODO”, “VJOURNAL”, or “VFREEBUSY” calendar components. Since RFC 7986, this property can also be defined on a “VCALENDAR”.

Example

The following is an example of this property:

URL:http://example.com/pub/calendars/jsmith/mytime.ics
class icalendar.cal.Available(*args, **kwargs)[source]#

Bases: Component

Sub-component of “VAVAILABILITY from RFC 7953.

Description:

“AVAILABLE” subcomponents are used to indicate periods of free time within the time range of the enclosing “VAVAILABILITY” component. “AVAILABLE” subcomponents MAY include recurrence properties to specify recurring periods of time, which can be overridden using normal iCalendar recurrence behavior (i.e., use of the “RECURRENCE-ID” property).

Examples

This is a recurring “AVAILABLE” subcomponent:

BEGIN:AVAILABLE
UID:57DD4AAF-3835-46B5-8A39-B3B253157F01
SUMMARY:Monday to Friday from 9:00 to 17:00
DTSTART;TZID=America/Denver:20111023T090000
DTEND;TZID=America/Denver:20111023T170000
RRULE:FREQ=WEEKLY;BYDAY=MO,TU,WE,TH,FR
LOCATION:Denver
END:AVAILABLE

You can get the same example from example():

property DTEND: datetime | None#

The DTEND property. datetime in UTC

All values will be converted to a datetime in UTC. Start of the component.

This is almost the same as Event.DTEND with one exception: The values MUST have a timezone and DATE is not allowed.

Description:

RFC 7953: If specified, the “DTSTART” and “DTEND” properties in “VAVAILABILITY” components and “AVAILABLE” subcomponents MUST be “DATE-TIME” values specified as either the date with UTC time or the date with local time and a time zone reference.

property DTSTART: datetime | None#

The DTSTART property. datetime in UTC

All values will be converted to a datetime in UTC. Start of the component.

This is almost the same as Event.DTSTART with one exception: The values MUST have a timezone and DATE is not allowed.

Description:

RFC 7953: If specified, the “DTSTART” and “DTEND” properties in “VAVAILABILITY” components and “AVAILABLE” subcomponents MUST be “DATE-TIME” values specified as either the date with UTC time or the date with local time and a time zone reference.

property DURATION: timedelta | None#

The DURATION property.

The “DTSTART” property for a “Available” specifies the inclusive start of the Available. The “DURATION” property in conjunction with the DTSTART property for a “Available” calendar component specifies the non-inclusive end of the event.

If you would like to calculate the duration of a Available, do not use this. Instead use the duration property (lower case).

property categories: list[str]#

This property defines the categories for a component.

Property Parameters:

IANA, non-standard, and language property parameters can be specified on this property.

Conformance:

The property can be specified within “VEVENT”, “VTODO”, or “VJOURNAL” calendar components. Since RFC 7986 it can also be defined on a “VCALENDAR” component.

Description:

This property is used to specify categories or subtypes of the calendar component. The categories are useful in searching for a calendar component of a particular type and category. Within the “VEVENT”, “VTODO”, or “VJOURNAL” calendar components, more than one category can be specified as a COMMA-separated list of categories.

Example

Below, we add the categories to an event:

>>> from icalendar import Event
>>> event = Event()
>>> event.categories = ["Work", "Meeting"]
>>> print(event.to_ical())
BEGIN:VEVENT
CATEGORIES:Work,Meeting
END:VEVENT
>>> event.categories.append("Lecture")
>>> event.categories == ["Work", "Meeting", "Lecture"]
True

Note

At present, we do not take the LANGUAGE parameter into account.

property contacts: list[str]#

Contact information associated with the calendar component.

Purpose:

This property is used to represent contact information or alternately a reference to contact information associated with the calendar component.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

In RFC 5545, this property can be specified in a “VEVENT”, “VTODO”, “VJOURNAL”, or “VFREEBUSY” calendar component. In RFC 7953, this property can be specified in a “VAVAILABILITY” amd “VAVAILABLE” calendar component.

Description:

The property value consists of textual contact information. An alternative representation for the property value can also be specified that refers to a URI pointing to an alternate form, such as a vCard RFC 2426, for the contact information.

Example

The following is an example of this property referencing textual contact information:

CONTACT:Jim Dolittle\, ABC Industries\, +1-919-555-1234

The following is an example of this property with an alternate representation of an LDAP URI to a directory entry containing the contact information:

CONTACT;ALTREP="ldap://example.com:6666/o=ABC%20Industries\,
c=US???(cn=Jim%20Dolittle)":Jim Dolittle\, ABC Industries\,
+1-919-555-1234

The following is an example of this property with an alternate representation of a MIME body part containing the contact information, such as a vCard RFC 2426 embedded in a text/ directory media type RFC 2425:

CONTACT;ALTREP="CID:part3.msg970930T083000SILVER@example.com":
 Jim Dolittle\, ABC Industries\, +1-919-555-1234

The following is an example of this property referencing a network resource, such as a vCard RFC 2426 object containing the contact information:

CONTACT;ALTREP="http://example.com/pdi/jdoe.vcf":Jim
 Dolittle\, ABC Industries\, +1-919-555-1234
property description: str | None#

DESCRIPTION provides a more complete description of the calendar component than that provided by the “SUMMARY” property.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

The property can be specified in the “VEVENT”, “VTODO”, “VJOURNAL”, or “VALARM” calendar components. The property can be specified multiple times only within a “VJOURNAL” calendar component.

Description:

This property is used in the “VEVENT” and “VTODO” to capture lengthy textual descriptions associated with the activity.

This property is used in the “VALARM” calendar component to capture the display text for a DISPLAY category of alarm, and to capture the body text for an EMAIL category of alarm.

Examples

The following is an example of this property with formatted line breaks in the property value:

DESCRIPTION:Meeting to provide technical review for "Phoenix"
 design.\nHappy Face Conference Room. Phoenix design team
 MUST attend this meeting.\nRSVP to team leader.
property duration: timedelta | None#

Compute the duration of this component.

If there is no DTEND or DURATION set, this is None. Otherwise, the duration is calculated from DTSTART and DTEND/DURATION.

This is in accordance with RFC 7953: If “DTEND” or “DURATION” are not present, then the end time is unbounded.

property end: timedelta | None#

Compute the duration of this component.

If there is no DTEND or DURATION set, this is None. Otherwise, the duration is calculated from DTSTART and DTEND/DURATION.

This is in accordance with RFC 7953: If “DTEND” or “DURATION” are not present, then the end time is unbounded.

classmethod example(name: str = 'rfc_7953_1') → Available[source]#

Return the calendar example with the given name.

property exdates: list[date | datetime]#

EXDATE defines the list of DATE-TIME exceptions for recurring components.

EXDATE is defined in RFC 5545.

Value Type:

The default value type for this property is DATE-TIME. The value type can be set to DATE.

Property Parameters:

IANA, non-standard, value data type, and time zone identifier property parameters can be specified on this property.

Conformance:

This property can be specified in recurring “VEVENT”, “VTODO”, and “VJOURNAL” calendar components as well as in the “STANDARD” and “DAYLIGHT” sub-components of the “VTIMEZONE” calendar component.

Description:

The exception dates, if specified, are used in computing the recurrence set. The recurrence set is the complete set of recurrence instances for a calendar component. The recurrence set is generated by considering the initial “DTSTART” property along with the “RRULE”, “RDATE”, and “EXDATE” properties contained within the recurring component. The “DTSTART” property defines the first instance in the recurrence set. The “DTSTART” property value SHOULD match the pattern of the recurrence rule, if specified. The recurrence set generated with a “DTSTART” property value that doesn’t match the pattern of the rule is undefined. The final recurrence set is generated by gathering all of the start DATE-TIME values generated by any of the specified “RRULE” and “RDATE” properties, and then excluding any start DATE-TIME values specified by “EXDATE” properties. This implies that start DATE-TIME values specified by “EXDATE” properties take precedence over those specified by inclusion properties (i.e., “RDATE” and “RRULE”). When duplicate instances are generated by the “RRULE” and “RDATE” properties, only one recurrence is considered. Duplicate instances are ignored.

The “EXDATE” property can be used to exclude the value specified in “DTSTART”. However, in such cases, the original “DTSTART” date MUST still be maintained by the calendaring and scheduling system because the original “DTSTART” value has inherent usage dependencies by other properties such as the “RECURRENCE-ID”.

Example

Below, we add an exdate in a list and get the resulting list of exdates.

>>> from icalendar import Event
>>> from datetime import datetime
>>> event = Event()

# Add a list of excluded dates
>>> event.add("EXDATE", [datetime(2025, 4, 28, 16, 5)])
>>> event.exdates
[datetime.datetime(2025, 4, 28, 16, 5)]

Note

You cannot modify the EXDATE value by modifying the result. Use icalendar.cal.Component.add() to add values.

If you want to compute recurrences, have a look at Related projects.

property location: str | None#

The intended venue for the activity defined by a calendar component.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

Since RFC 5545, this property can be specified in “VEVENT” or “VTODO” calendar component. RFC 7953 adds this property to “VAVAILABILITY” and “VAVAILABLE”.

Description:

Specific venues such as conference or meeting rooms may be explicitly specified using this property. An alternate representation may be specified that is a URI that points to directory information with more structured specification of the location. For example, the alternate representation may specify either an LDAP URL RFC 4516 pointing to an LDAP server entry or a CID URL RFC 2392 pointing to a MIME body part containing a Virtual-Information Card (vCard) RFC 2426 for the location.

name = 'VAVAILABLE'#
classmethod new(categories: Sequence[str] = (), comments: list[str] | str | None = None, contacts: list[str] | str | None = None, created: date | None = None, description: str | None = None, end: datetime | None = None, last_modified: date | None = None, location: str | None = None, sequence: int | None = None, stamp: date | None = None, start: datetime | None = None, summary: str | None = None, uid: str | uuid.UUID | None = None)[source]#

Create a new Available component with all required properties.

This creates a new Available component in accordance with RFC 7953.

Parameters:

  • categories – The categories of the Available component.

  • comments – The Component.comments of the Available component.

  • contacts – The contacts of the Available component.

  • created – The Component.created of the Available component.

  • description – The description of the Available component.

  • last_modified – The Component.last_modified of the Available component.

  • location – The location of the Available component.

  • sequence – The sequence of the Available component.

  • stamp – The Component.stamp of the Available component. If None, this is set to the current time.

  • summary – The summary of the Available component.

  • uid – The uid of the Available component. If None, this is set to a new uuid.uuid4().

Returns:

Available

Raises:

InvalidCalendar – If the content is not valid according to RFC 7953.

Warning

As time progresses, we will be stricter with the validation.

property rdates: list[tuple[date, None] | tuple[datetime, None] | tuple[datetime, datetime]]#

The RDATE property defines the list of DATE-TIME values for recurring components.

RDATE is defined in RFC 5545. The return value is a list of tuples (start, end).

start can be a datetime.date or a datetime.datetime, with and without timezone.

end is None if the end is not specified and a datetime.datetime if the end is specified.

Value Type:

The default value type for this property is DATE-TIME. The value type can be set to DATE or PERIOD.

Property Parameters:

IANA, non-standard, value data type, and time zone identifier property parameters can be specified on this property.

Conformance:

This property can be specified in recurring “VEVENT”, “VTODO”, and “VJOURNAL” calendar components as well as in the “STANDARD” and “DAYLIGHT” sub-components of the “VTIMEZONE” calendar component.

Description:

This property can appear along with the “RRULE” property to define an aggregate set of repeating occurrences. When they both appear in a recurring component, the recurrence instances are defined by the union of occurrences defined by both the “RDATE” and “RRULE”.

The recurrence dates, if specified, are used in computing the recurrence set. The recurrence set is the complete set of recurrence instances for a calendar component. The recurrence set is generated by considering the initial “DTSTART” property along with the “RRULE”, “RDATE”, and “EXDATE” properties contained within the recurring component. The “DTSTART” property defines the first instance in the recurrence set. The “DTSTART” property value SHOULD match the pattern of the recurrence rule, if specified. The recurrence set generated with a “DTSTART” property value that doesn’t match the pattern of the rule is undefined. The final recurrence set is generated by gathering all of the start DATE-TIME values generated by any of the specified “RRULE” and “RDATE” properties, and then excluding any start DATE-TIME values specified by “EXDATE” properties. This implies that start DATE-TIME values specified by “EXDATE” properties take precedence over those specified by inclusion properties (i.e., “RDATE” and “RRULE”). Where duplicate instances are generated by the “RRULE” and “RDATE” properties, only one recurrence is considered. Duplicate instances are ignored.

Example

Below, we set one RDATE in a list and get the resulting tuple of start and end.

>>> from icalendar import Event
>>> from datetime import datetime
>>> event = Event()

# Add a list of recurrence dates
>>> event.add("RDATE", [datetime(2025, 4, 28, 16, 5)])
>>> event.rdates
[(datetime.datetime(2025, 4, 28, 16, 5), None)]

Note

You cannot modify the RDATE value by modifying the result. Use icalendar.cal.Component.add() to add values.

If you want to compute recurrences, have a look at Related projects.

property rrules: list[vRecur]#

RRULE defines a rule or repeating pattern for recurring components.

RRULE is defined in RFC 5545. RFC 7529 adds the SKIP parameter icalendar.prop.vSkip.

Property Parameters:

IANA and non-standard property parameters can be specified on this property.

Conformance:

This property can be specified in recurring “VEVENT”, “VTODO”, and “VJOURNAL” calendar components as well as in the “STANDARD” and “DAYLIGHT” sub-components of the “VTIMEZONE” calendar component, but it SHOULD NOT be specified more than once. The recurrence set generated with multiple “RRULE” properties is undefined.

Description:

The recurrence rule, if specified, is used in computing the recurrence set. The recurrence set is the complete set of recurrence instances for a calendar component. The recurrence set is generated by considering the initial “DTSTART” property along with the “RRULE”, “RDATE”, and “EXDATE” properties contained within the recurring component. The “DTSTART” property defines the first instance in the recurrence set. The “DTSTART” property value SHOULD be synchronized with the recurrence rule, if specified. The recurrence set generated with a “DTSTART” property value not synchronized with the recurrence rule is undefined. The final recurrence set is generated by gathering all of the start DATE-TIME values generated by any of the specified “RRULE” and “RDATE” properties, and then excluding any start DATE-TIME values specified by “EXDATE” properties. This implies that start DATE- TIME values specified by “EXDATE” properties take precedence over those specified by inclusion properties (i.e., “RDATE” and “RRULE”). Where duplicate instances are generated by the “RRULE” and “RDATE” properties, only one recurrence is considered. Duplicate instances are ignored.

The “DTSTART” property specified within the iCalendar object defines the first instance of the recurrence. In most cases, a “DTSTART” property of DATE-TIME value type used with a recurrence rule, should be specified as a date with local time and time zone reference to make sure all the recurrence instances start at the same local time regardless of time zone changes.

If the duration of the recurring component is specified with the “DTEND” or “DUE” property, then the same exact duration will apply to all the members of the generated recurrence set. Else, if the duration of the recurring component is specified with the “DURATION” property, then the same nominal duration will apply to all the members of the generated recurrence set and the exact duration of each recurrence instance will depend on its specific start time. For example, recurrence instances of a nominal duration of one day will have an exact duration of more or less than 24 hours on a day where a time zone shift occurs. The duration of a specific recurrence may be modified in an exception component or simply by using an “RDATE” property of PERIOD value type.

Examples

Daily for 10 occurrences:

>>> from icalendar import Event
>>> from datetime import datetime
>>> from zoneinfo import ZoneInfo
>>> event = Event()
>>> event.start = datetime(1997, 9, 2, 9, 0, tzinfo=ZoneInfo("America/New_York"))
>>> event.add("RRULE", "FREQ=DAILY;COUNT=10")
>>> print(event.to_ical())
BEGIN:VEVENT
DTSTART;TZID=America/New_York:19970902T090000
RRULE:FREQ=DAILY;COUNT=10
END:VEVENT
>>> event.rrules
[vRecur({'FREQ': ['DAILY'], 'COUNT': [10]})]

Daily until December 24, 1997:

>>> from icalendar import Event, vRecur
>>> from datetime import datetime
>>> from zoneinfo import ZoneInfo
>>> event = Event()
>>> event.start = datetime(1997, 9, 2, 9, 0, tzinfo=ZoneInfo("America/New_York"))
>>> event.add("RRULE", vRecur({"FREQ": ["DAILY"]}, until=datetime(1997, 12, 24, tzinfo=ZoneInfo("UTC"))))
>>> print(event.to_ical())
BEGIN:VEVENT
DTSTART;TZID=America/New_York:19970902T090000
RRULE:FREQ=DAILY;UNTIL=19971224T000000Z
END:VEVENT
>>> event.rrules
[vRecur({'FREQ': ['DAILY'], 'UNTIL': [datetime.datetime(1997, 12, 24, 0, 0, tzinfo=ZoneInfo(key='UTC'))]})]

Note

You cannot modify the RRULE value by modifying the result. Use icalendar.cal.Component.add() to add values.

If you want to compute recurrences, have a look at Related projects.

property sequence: int#

This property defines the revision sequence number of the calendar component within a sequence of revisions.

Value Type:

INTEGER

Property Parameters:

IANA and non-standard property parameters can be specified on this property.

Conformance:

The property can be specified in “VEVENT”, “VTODO”, or “VJOURNAL” calendar component.

Description:

When a calendar component is created, its sequence number is 0. It is monotonically incremented by the “Organizer’s” CUA each time the “Organizer” makes a significant revision to the calendar component.

The “Organizer” includes this property in an iCalendar object that it sends to an “Attendee” to specify the current version of the calendar component.

The “Attendee” includes this property in an iCalendar object that it sends to the “Organizer” to specify the version of the calendar component to which the “Attendee” is referring.

A change to the sequence number is not the mechanism that an “Organizer” uses to request a response from the “Attendees”. The “RSVP” parameter on the “ATTENDEE” property is used by the “Organizer” to indicate that a response from the “Attendees” is requested.

Recurrence instances of a recurring component MAY have different sequence numbers.

Examples

The following is an example of this property for a calendar component that was just created by the “Organizer”:

>>> from icalendar import Event
>>> event = Event()
>>> event.sequence
0

The following is an example of this property for a calendar component that has been revised 10 different times by the “Organizer”:

>>> from icalendar import Calendar
>>> calendar = Calendar.example("issue_156_RDATE_with_PERIOD_TZID_khal")
>>> event = calendar.events[0]
>>> event.sequence
10
property start: datetime | None#

The DTSTART property. datetime in UTC

All values will be converted to a datetime in UTC. Start of the component.

This is almost the same as Event.DTSTART with one exception: The values MUST have a timezone and DATE is not allowed.

Description:

RFC 7953: If specified, the “DTSTART” and “DTEND” properties in “VAVAILABILITY” components and “AVAILABLE” subcomponents MUST be “DATE-TIME” values specified as either the date with UTC time or the date with local time and a time zone reference.

subcomponents: list[Component]#
property summary: str | None#

SUMMARY defines a short summary or subject for the calendar component.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

The property can be specified in “VEVENT”, “VTODO”, “VJOURNAL”, or “VALARM” calendar components.

Description:

This property is used in the “VEVENT”, “VTODO”, and “VJOURNAL” calendar components to capture a short, one-line summary about the activity or journal entry.

This property is used in the “VALARM” calendar component to capture the subject of an EMAIL category of alarm.

Examples

The following is an example of this property:

SUMMARY:Department Party
property uid: str#

UID specifies the persistent, globally unique identifier for a component.

We recommend using uuid.uuid4() to generate new values.

Returns:

The value of the UID property as a string or "" if no value is set.

Description:

The “UID” itself MUST be a globally unique identifier. The generator of the identifier MUST guarantee that the identifier is unique.

This is the method for correlating scheduling messages with the referenced “VEVENT”, “VTODO”, or “VJOURNAL” calendar component. The full range of calendar components specified by a recurrence set is referenced by referring to just the “UID” property value corresponding to the calendar component. The “RECURRENCE-ID” property allows the reference to an individual instance within the recurrence set.

This property is an important method for group-scheduling applications to match requests with later replies, modifications, or deletion requests. Calendaring and scheduling applications MUST generate this property in “VEVENT”, “VTODO”, and “VJOURNAL” calendar components to assure interoperability with other group- scheduling applications. This identifier is created by the calendar system that generates an iCalendar object.

Implementations MUST be able to receive and persist values of at least 255 octets for this property, but they MUST NOT truncate values in the middle of a UTF-8 multi-octet sequence.

RFC 7986 states that UID can be used, for example, to identify duplicate calendar streams that a client may have been given access to. It can be used in conjunction with the “LAST-MODIFIED” property also specified on the “VCALENDAR” object to identify the most recent version of a calendar.

Conformance:

RFC 5545 states that the “UID” property can be specified on “VEVENT”, “VTODO”, and “VJOURNAL” calendar components. RFC 7986 modifies the definition of the “UID” property to allow it to be defined in an iCalendar object. RFC 9074 adds a “UID” property to “VALARM” components to allow a unique identifier to be specified. The value of this property can then be used to refer uniquely to the “VALARM” component.

This property can be specified once only.

Security:

RFC 7986 states that UID values MUST NOT include any data that might identify a user, host, domain, or any other security- or privacy-sensitive information. It is RECOMMENDED that calendar user agents now generate “UID” values that are hex-encoded random Universally Unique Identifier (UUID) values as defined in Sections 4.4 and 4.5 of RFC 4122. You can use the uuid module to generate new UUIDs.

Compatibility:

For Alarms, X-ALARMUID is also considered.

Examples

The following is an example of such a property value: 5FC53010-1267-4F8E-BC28-1D7AE55A7C99.

Set the UID of a calendar:

>>> from icalendar import Calendar
>>> from uuid import uuid4
>>> calendar = Calendar()
>>> calendar.uid = uuid4()
>>> print(calendar.to_ical())
BEGIN:VCALENDAR
UID:d755cef5-2311-46ed-a0e1-6733c9e15c63
END:VCALENDAR
class icalendar.cal.Calendar(*args, **kwargs)[source]#

Bases: Component

The “VCALENDAR” object is a collection of calendar information. This information can include a variety of components, such as “VEVENT”, “VTODO”, “VJOURNAL”, “VFREEBUSY”, “VTIMEZONE”, or any other type of calendar component.

Examples

Create a new Calendar:

>>> from icalendar import Calendar
>>> calendar = Calendar.new(name="My Calendar")
>>> print(calendar.calendar_name)
My Calendar
add_missing_timezones(first_date: date = datetime.date(1970, 1, 1), last_date: date = datetime.date(2038, 1, 1))[source]#

Add all missing VTIMEZONE components.

This adds all the timezone components that are required. VTIMEZONE components are inserted at the beginning of the calendar to ensure they appear before other components that reference them.

Note

Timezones that are not known will not be added.

Parameters:

  • first_date – earlier than anything that happens in the calendar

  • last_date – later than anything happening in the calendar

>>> from icalendar import Calendar, Event
>>> from datetime import datetime
>>> from zoneinfo import ZoneInfo
>>> calendar = Calendar()
>>> event = Event()
>>> calendar.add_component(event)
>>> event.start = datetime(1990, 10, 11, 12, tzinfo=ZoneInfo("Europe/Berlin"))
>>> calendar.timezones
[]
>>> calendar.add_missing_timezones()
>>> calendar.timezones[0].tz_name
'Europe/Berlin'
>>> calendar.get_missing_tzids()  # check that all are added
set()
property availabilities: list[Availability]#

All Availability components in the calendar.

This is a shortcut to get all availabilities. Modifications do not change the calendar. Use Component.add_component().

property calendar_name: str | None#

This property specifies the name of the calendar.

This implements RFC 7986 NAME and X-WR-CALNAME.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

This property can be specified multiple times in an iCalendar object. However, each property MUST represent the name of the calendar in a different language.

Description:

This property is used to specify a name of the iCalendar object that can be used by calendar user agents when presenting the calendar data to a user. Whilst a calendar only has a single name, multiple language variants can be specified by including this property multiple times with different “LANGUAGE” parameter values on each.

Example

Below, we set the name of the calendar.

>>> from icalendar import Calendar
>>> calendar = Calendar()
>>> calendar.calendar_name = "My Calendar"
>>> print(calendar.to_ical())
BEGIN:VCALENDAR
NAME:My Calendar
END:VCALENDAR
property calscale: str#

CALSCALE defines the calendar scale used for the calendar information specified in the iCalendar object.

Compatibility:

RFC 7529 makes the case that GREGORIAN stays the default and other calendar scales are implemented on the RRULE.

Conformance:

This property can be specified once in an iCalendar object. The default value is “GREGORIAN”.

Description:

This memo is based on the Gregorian calendar scale. The Gregorian calendar scale is assumed if this property is not specified in the iCalendar object. It is expected that other calendar scales will be defined in other specifications or by future versions of this memo.

canonical_order = ('VERSION', 'PRODID', 'CALSCALE', 'METHOD', 'DESCRIPTION', 'X-WR-CALDESC', 'NAME', 'X-WR-CALNAME')#
property categories: list[str]#

This property defines the categories for a component.

Property Parameters:

IANA, non-standard, and language property parameters can be specified on this property.

Conformance:

The property can be specified within “VEVENT”, “VTODO”, or “VJOURNAL” calendar components. Since RFC 7986 it can also be defined on a “VCALENDAR” component.

Description:

This property is used to specify categories or subtypes of the calendar component. The categories are useful in searching for a calendar component of a particular type and category. Within the “VEVENT”, “VTODO”, or “VJOURNAL” calendar components, more than one category can be specified as a COMMA-separated list of categories.

Example

Below, we add the categories to an event:

>>> from icalendar import Event
>>> event = Event()
>>> event.categories = ["Work", "Meeting"]
>>> print(event.to_ical())
BEGIN:VEVENT
CATEGORIES:Work,Meeting
END:VEVENT
>>> event.categories.append("Lecture")
>>> event.categories == ["Work", "Meeting", "Lecture"]
True

Note

At present, we do not take the LANGUAGE parameter into account.

property color: str#

This property specifies a color used for displaying the calendar.

This implements RFC 7986 COLOR and X-APPLE-CALENDAR-COLOR. Please note that since RFC 7986, subcomponents can have their own color.

Property Parameters:

IANA and non-standard property parameters can be specified on this property.

Conformance:

This property can be specified once in an iCalendar object or in VEVENT, VTODO, or VJOURNAL calendar components.

Description:

This property specifies a color that clients MAY use when presenting the relevant data to a user. Typically, this would appear as the “background” color of events or tasks. The value is a case-insensitive color name taken from the CSS3 set of names, defined in Section 4.3 of W3C.REC-css3-color-20110607.

Example

"turquoise", "#ffffff"

>>> from icalendar import Calendar
>>> calendar = Calendar()
>>> calendar.color = "black"
>>> print(calendar.to_ical())
BEGIN:VCALENDAR
COLOR:black
END:VCALENDAR
property description: str | None#

This property specifies the description of the calendar.

This implements RFC 7986 DESCRIPTION and X-WR-CALDESC.

Conformance:

This property can be specified multiple times in an iCalendar object. However, each property MUST represent the description of the calendar in a different language.

Description:

This property is used to specify a lengthy textual description of the iCalendar object that can be used by calendar user agents when describing the nature of the calendar data to a user. Whilst a calendar only has a single description, multiple language variants can be specified by including this property multiple times with different “LANGUAGE” parameter values on each.

Example

Below, we add a description to a calendar.

>>> from icalendar import Calendar
>>> calendar = Calendar()
>>> calendar.description = "This is a calendar"
>>> print(calendar.to_ical())
BEGIN:VCALENDAR
DESCRIPTION:This is a calendar
END:VCALENDAR
property events: list[Event]#

All event components in the calendar.

This is a shortcut to get all events. Modifications do not change the calendar. Use Component.add_component().

>>> from icalendar import Calendar
>>> calendar = Calendar.example()
>>> event = calendar.events[0]
>>> event.start
datetime.date(2022, 1, 1)
>>> print(event["SUMMARY"])
New Year's Day
classmethod example(name: str = 'example') → Calendar[source]#

Return the calendar example with the given name.

property freebusy: list[FreeBusy]#

All FreeBusy components in the calendar.

This is a shortcut to get all FreeBusy. Modifications do not change the calendar. Use Component.add_component().

classmethod from_ical(st, multiple=False)[source]#

Populates the component recursively from a string.

get_missing_tzids() → set[str][source]#

The set of missing timezone component tzids.

To create a RFC 5545 compatible calendar, all of these timezones should be added.

get_used_tzids() → set[str][source]#

The set of TZIDs in use.

This goes through the whole calendar to find all occurrences of timezone information like the TZID parameter in all attributes.

>>> from icalendar import Calendar
>>> calendar = Calendar.example("timezone_rdate")
>>> calendar.get_used_tzids()
{'posix/Europe/Vaduz'}

Even if you use UTC, this will not show up.

property images: list[Image]#

IMAGE specifies an image associated with the calendar or a calendar component.

Description:

This property specifies an image for an iCalendar object or a calendar component via a URI or directly with inline data that can be used by calendar user agents when presenting the calendar data to a user. Multiple properties MAY be used to specify alternative sets of images with, for example, varying media subtypes, resolutions, or sizes. When multiple properties are present, calendar user agents SHOULD display only one of them, picking one that provides the most appropriate image quality, or display none. The “DISPLAY” parameter is used to indicate the intended display mode for the image. The “ALTREP” parameter, defined in RFC 5545, can be used to provide a “clickable” image where the URI in the parameter value can be “launched” by a click on the image in the calendar user agent.

Conformance:

This property can be specified multiple times in an iCalendar object or in “VEVENT”, “VTODO”, or “VJOURNAL” calendar components.

Note

At the present moment, this property is read-only. If you require a setter, please open an issue or a pull request.

property method: str#

METHOD defines the iCalendar object method associated with the calendar object.

Description:

When used in a MIME message entity, the value of this property MUST be the same as the Content-Type “method” parameter value. If either the “METHOD” property or the Content-Type “method” parameter is specified, then the other MUST also be specified.

No methods are defined by this specification. This is the subject of other specifications, such as the iCalendar Transport- independent Interoperability Protocol (iTIP) defined by RFC 5546.

If this property is not present in the iCalendar object, then a scheduling transaction MUST NOT be assumed. In such cases, the iCalendar object is merely being used to transport a snapshot of some calendar information; without the intention of conveying a scheduling semantic.

multiple = ('CATEGORIES', 'DESCRIPTION', 'NAME')#
name = 'VCALENDAR'#
classmethod new(calscale: str | None = None, categories: Sequence[str] = (), color: str | None = None, description: str | None = None, language: str | None = None, last_modified: date | datetime | None = None, method: str | None = None, name: str | None = None, organization: str | None = None, prodid: str | None = None, refresh_interval: timedelta | None = None, source: str | None = None, uid: str | uuid.UUID | None = None, url: str | None = None, version: str = '2.0')[source]#

Create a new Calendar with all required properties.

This creates a new Calendar in accordance with RFC 5545 and RFC 7986.

Parameters:

  • calscale – The calscale of the calendar.

  • categories – The categories of the calendar.

  • color – The color of the calendar.

  • description – The description of the calendar.

  • language – The language for the calendar. Used to generate localized prodid.

  • last_modified – The Component.last_modified of the calendar.

  • method – The method of the calendar.

  • name – The calendar_name of the calendar.

  • organization – The organization name. Used to generate prodid if not provided.

  • prodid – The prodid of the component. If None and organization is provided, generates a prodid in format “-//organization//name//language”.

  • refresh_interval – The refresh_interval of the calendar.

  • source – The source of the calendar.

  • uid – The uid of the calendar. If None, this is set to a new uuid.uuid4().

  • url – The url of the calendar.

  • version – The version of the calendar.

Returns:

Calendar

Raises:

InvalidCalendar – If the content is not valid according to RFC 5545.

Warning

As time progresses, we will be stricter with the validation.

property prodid: str#

PRODID specifies the identifier for the product that created the iCalendar object.

Conformance:

The property MUST be specified once in an iCalendar object.

Description:

The vendor of the implementation SHOULD assure that this is a globally unique identifier; using some technique such as an FPI value, as defined in [ISO.9070.1991].

This property SHOULD NOT be used to alter the interpretation of an iCalendar object beyond the semantics specified in this memo. For example, it is not to be used to further the understanding of non- standard properties.

Example

The following is an example of this property. It does not imply that English is the default language.

-//ABC Corporation//NONSGML My Product//EN
property refresh_interval: timedelta | None#

REFRESH-INTERVAL specifies a suggested minimum interval for polling for changes of the calendar data from the original source of that data.

Conformance:

This property can be specified once in an iCalendar object, consisting of a positive duration of time.

Description:

This property specifies a positive duration that gives a suggested minimum polling interval for checking for updates to the calendar data. The value of this property SHOULD be used by calendar user agents to limit the polling interval for calendar data updates to the minimum interval specified.

Raises:

ValueError – When setting a negative duration.

required = ('PRODID', 'VERSION')#
singletons = ('PRODID', 'VERSION', 'CALSCALE', 'METHOD', 'COLOR')#
property source: str#

A URI from where calendar data can be refreshed.

Description:

This property identifies a location where a client can retrieve updated data for the calendar. Clients SHOULD honor any specified “REFRESH-INTERVAL” value when periodically retrieving data. Note that this property differs from the “URL” property in that “URL” is meant to provide an alternative representation of the calendar data rather than the original location of the data.

Conformance:

This property can be specified once in an iCalendar object.

Example

The following is an example of this property:

SOURCE;VALUE=URI:https://example.com/holidays.ics
subcomponents: list[Component]#
property timezones: list[Timezone]#

Return the timezones components in this calendar.

>>> from icalendar import Calendar
>>> calendar = Calendar.example("pacific_fiji")
>>> [timezone.tz_name for timezone in calendar.timezones]
['custom_Pacific/Fiji']

Note

This is a read-only property.

property todos: list[Todo]#

All todo components in the calendar.

This is a shortcut to get all todos. Modifications do not change the calendar. Use Component.add_component().

property uid: str#

UID specifies the persistent, globally unique identifier for a component.

We recommend using uuid.uuid4() to generate new values.

Returns:

The value of the UID property as a string or "" if no value is set.

Description:

The “UID” itself MUST be a globally unique identifier. The generator of the identifier MUST guarantee that the identifier is unique.

This is the method for correlating scheduling messages with the referenced “VEVENT”, “VTODO”, or “VJOURNAL” calendar component. The full range of calendar components specified by a recurrence set is referenced by referring to just the “UID” property value corresponding to the calendar component. The “RECURRENCE-ID” property allows the reference to an individual instance within the recurrence set.

This property is an important method for group-scheduling applications to match requests with later replies, modifications, or deletion requests. Calendaring and scheduling applications MUST generate this property in “VEVENT”, “VTODO”, and “VJOURNAL” calendar components to assure interoperability with other group- scheduling applications. This identifier is created by the calendar system that generates an iCalendar object.

Implementations MUST be able to receive and persist values of at least 255 octets for this property, but they MUST NOT truncate values in the middle of a UTF-8 multi-octet sequence.

RFC 7986 states that UID can be used, for example, to identify duplicate calendar streams that a client may have been given access to. It can be used in conjunction with the “LAST-MODIFIED” property also specified on the “VCALENDAR” object to identify the most recent version of a calendar.

Conformance:

RFC 5545 states that the “UID” property can be specified on “VEVENT”, “VTODO”, and “VJOURNAL” calendar components. RFC 7986 modifies the definition of the “UID” property to allow it to be defined in an iCalendar object. RFC 9074 adds a “UID” property to “VALARM” components to allow a unique identifier to be specified. The value of this property can then be used to refer uniquely to the “VALARM” component.

This property can be specified once only.

Security:

RFC 7986 states that UID values MUST NOT include any data that might identify a user, host, domain, or any other security- or privacy-sensitive information. It is RECOMMENDED that calendar user agents now generate “UID” values that are hex-encoded random Universally Unique Identifier (UUID) values as defined in Sections 4.4 and 4.5 of RFC 4122. You can use the uuid module to generate new UUIDs.

Compatibility:

For Alarms, X-ALARMUID is also considered.

Examples

The following is an example of such a property value: 5FC53010-1267-4F8E-BC28-1D7AE55A7C99.

Set the UID of a calendar:

>>> from icalendar import Calendar
>>> from uuid import uuid4
>>> calendar = Calendar()
>>> calendar.uid = uuid4()
>>> print(calendar.to_ical())
BEGIN:VCALENDAR
UID:d755cef5-2311-46ed-a0e1-6733c9e15c63
END:VCALENDAR
property url: str#

A Uniform Resource Locator (URL) associated with the iCalendar object.

Description:

This property may be used in a calendar component to convey a location where a more dynamic rendition of the calendar information associated with the calendar component can be found. This memo does not attempt to standardize the form of the URI, nor the format of the resource pointed to by the property value. If the URL property and Content-Location MIME header are both specified, they MUST point to the same resource.

Conformance:

This property can be specified once in the “VEVENT”, “VTODO”, “VJOURNAL”, or “VFREEBUSY” calendar components. Since RFC 7986, this property can also be defined on a “VCALENDAR”.

Example

The following is an example of this property:

URL:http://example.com/pub/calendars/jsmith/mytime.ics
validate()[source]#

Validate that the calendar has required properties and components.

This method can be called explicitly to validate a calendar before output.

Raises:

IncompleteComponent – If the calendar lacks required properties or components.

property version: str#

VERSION of the calendar specification.

The default is "2.0" for RFC 5545.

Purpose:

This property specifies the identifier corresponding to the highest version number or the minimum and maximum range of the iCalendar specification that is required in order to interpret the iCalendar object.

class icalendar.cal.Component(*args, **kwargs)[source]#

Bases: CaselessDict

Base class for calendar components.

Component is the base object for calendar, Event and the other components defined in RFC 5545. Normally you will not use this class directly, but rather one of the subclasses.

name#

The name of the component. Example: VCALENDAR.

required#

These properties are required.

singletons#

These properties must only appear once.

multiple#

These properties may occur more than once.

exclusive#

These properties are mutually exclusive.

inclusive#

If the first in a tuple occurs, the second one must also occur.

Type:

tuple[str] | tuple[tuple[str, str]]

ignore_exceptions#

If True, and we cannot parse this component, we will silently ignore it, rather than let the exception propagate upwards.

types_factory#

Factory for property types

property CREATED: datetime | None#

The CREATED property. datetime in UTC

All values will be converted to a datetime in UTC.

CREATED specifies the date and time that the calendar information was created by the calendar user agent in the calendar store.

Conformance:

The property can be specified once in “VEVENT”, “VTODO”, or “VJOURNAL” calendar components. The value MUST be specified as a date with UTC time.

property DTSTAMP: datetime | None#

The DTSTAMP property. datetime in UTC

All values will be converted to a datetime in UTC. RFC 5545:

Conformance: This property MUST be included in the “VEVENT”, “VTODO”, “VJOURNAL”, or “VFREEBUSY” calendar components.

Description: In the case of an iCalendar object that specifies a “METHOD” property, this property specifies the date and time that the instance of the iCalendar object was created. In the case of an iCalendar object that doesn’t specify a “METHOD” property, this property specifies the date and time that the information associated with the calendar component was last revised in the calendar store.

The value MUST be specified in the UTC time format.

In the case of an iCalendar object that doesn’t specify a “METHOD” property, this property is equivalent to the “LAST-MODIFIED” property.

property LAST_MODIFIED: datetime | None#

The LAST-MODIFIED property. datetime in UTC

All values will be converted to a datetime in UTC. RFC 5545:

Purpose: This property specifies the date and time that the information associated with the calendar component was last revised in the calendar store.

Note: This is analogous to the modification date and time for a file in the file system.

Conformance: This property can be specified in the “VEVENT”, “VTODO”, “VJOURNAL”, or “VTIMEZONE” calendar components.

add(name: str, value, parameters: dict[str, str] | Parameters = None, encode: bool = True)[source]#

Add a property.

Parameters:

  • name (string) – Name of the property.

  • value (Python native type or icalendar property type.) – Value of the property. Either of a basic Python type of any of the icalendar’s own property types.

  • parameters (Dictionary) – Property parameter dictionary for the value. Only available, if encode is set to True.

  • encode (Boolean) – True, if the value should be encoded to one of icalendar’s own property types (Fallback is “vText”) or False, if not.

Returns:

None

add_component(component: Component)[source]#

Add a subcomponent to this component.

property comments: list[str]#

COMMENT is used to specify a comment to the calendar user.

Purpose:

This property specifies non-processing information intended to provide a comment to the calendar user.

Conformance:

In RFC 5545, this property can be specified multiple times in “VEVENT”, “VTODO”, “VJOURNAL”, and “VFREEBUSY” calendar components as well as in the “STANDARD” and “DAYLIGHT” sub-components. In RFC 7953, this property can be specified multiple times in “VAVAILABILITY” and “VAVAILABLE”.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

content_line(name, value, sorted: bool = True)[source]#

Returns property as content line.

content_lines(sorted: bool = True)[source]#

Converts the Component and subcomponents into content lines.

property created: datetime#

Datetime when the information associated with the component was created.

Since CREATED is an optional property, this returns DTSTAMP if CREATED is not set.

decoded(name, default=[])[source]#

Returns decoded value of property.

exclusive = ()#
classmethod from_ical(st, multiple: bool = False) → Self | list[Self][source]#

Populates the component recursively from a string.

classmethod get_component_class(name: str) → type[Component][source]#

Return a component with this name.

Parameters:

name – Name of the component, i.e. VCALENDAR

get_inline(name, decode=1)[source]#

Returns a list of values (split on comma).

ignore_exceptions = False#
inclusive: tuple[str] | tuple[tuple[str, str]] = ()#
is_empty()[source]#

Returns True if Component has no items or subcomponents, else False.

is_thunderbird() → bool[source]#

Whether this component has attributes that indicate that Mozilla Thunderbird created it.

property last_modified: datetime#

Datetime when the information associated with the component was last revised.

Since LAST_MODIFIED is an optional property, this returns DTSTAMP if LAST_MODIFIED is not set.

multiple = ()#
name = None#
classmethod new(created: date | None = None, comments: list[str] | str | None = None, last_modified: date | None = None, stamp: date | None = None) → Component[source]#

Create a new component.

Parameters:

  • comments – The comments of the component.

  • created – The created of the component.

  • last_modified – The last_modified of the component.

  • stamp – The DTSTAMP of the component.

Raises:

InvalidCalendar – If the content is not valid according to RFC 5545.

Warning

As time progresses, we will be stricter with the validation.

property_items(recursive=True, sorted: bool = True) → list[tuple[str, object]][source]#

Returns properties in this component and subcomponents as: [(name, value), …]

required = ()#
set_inline(name, values, encode=1)[source]#

Converts a list of values into comma separated string and sets value to that.

singletons = ()#
property stamp: datetime | None#

The DTSTAMP property. datetime in UTC

All values will be converted to a datetime in UTC. RFC 5545:

Conformance: This property MUST be included in the “VEVENT”, “VTODO”, “VJOURNAL”, or “VFREEBUSY” calendar components.

Description: In the case of an iCalendar object that specifies a “METHOD” property, this property specifies the date and time that the instance of the iCalendar object was created. In the case of an iCalendar object that doesn’t specify a “METHOD” property, this property specifies the date and time that the information associated with the calendar component was last revised in the calendar store.

The value MUST be specified in the UTC time format.

In the case of an iCalendar object that doesn’t specify a “METHOD” property, this property is equivalent to the “LAST-MODIFIED” property.

subcomponents: list[Component]#
to_ical(sorted: bool = True)[source]#
Parameters:

sorted – Whether parameters and properties should be lexicographically sorted.

types_factory = {'BINARY': <class 'icalendar.prop.vBinary'>, 'BOOLEAN': <class 'icalendar.prop.vBoolean'>, 'CAL-ADDRESS': <class 'icalendar.prop.vCalAddress'>, 'CATEGORIES': <class 'icalendar.prop.vCategory'>, 'DATE': <class 'icalendar.prop.vDDDTypes'>, 'DATE-TIME': <class 'icalendar.prop.vDDDTypes'>, 'DATE-TIME-LIST': <class 'icalendar.prop.vDDDLists'>, 'DURATION': <class 'icalendar.prop.vDDDTypes'>, 'FLOAT': <class 'icalendar.prop.vFloat'>, 'GEO': <class 'icalendar.prop.vGeo'>, 'INLINE': <class 'icalendar.prop.vInline'>, 'INTEGER': <class 'icalendar.prop.vInt'>, 'PERIOD': <class 'icalendar.prop.vPeriod'>, 'RECUR': <class 'icalendar.prop.vRecur'>, 'TEXT': <class 'icalendar.prop.vText'>, 'TIME': <class 'icalendar.prop.vTime'>, 'URI': <class 'icalendar.prop.vUri'>, 'UTC-OFFSET': <class 'icalendar.prop.vUTCOffset'>}#
property uid: str#

UID specifies the persistent, globally unique identifier for a component.

We recommend using uuid.uuid4() to generate new values.

Returns:

The value of the UID property as a string or "" if no value is set.

Description:

The “UID” itself MUST be a globally unique identifier. The generator of the identifier MUST guarantee that the identifier is unique.

This is the method for correlating scheduling messages with the referenced “VEVENT”, “VTODO”, or “VJOURNAL” calendar component. The full range of calendar components specified by a recurrence set is referenced by referring to just the “UID” property value corresponding to the calendar component. The “RECURRENCE-ID” property allows the reference to an individual instance within the recurrence set.

This property is an important method for group-scheduling applications to match requests with later replies, modifications, or deletion requests. Calendaring and scheduling applications MUST generate this property in “VEVENT”, “VTODO”, and “VJOURNAL” calendar components to assure interoperability with other group- scheduling applications. This identifier is created by the calendar system that generates an iCalendar object.

Implementations MUST be able to receive and persist values of at least 255 octets for this property, but they MUST NOT truncate values in the middle of a UTF-8 multi-octet sequence.

RFC 7986 states that UID can be used, for example, to identify duplicate calendar streams that a client may have been given access to. It can be used in conjunction with the “LAST-MODIFIED” property also specified on the “VCALENDAR” object to identify the most recent version of a calendar.

Conformance:

RFC 5545 states that the “UID” property can be specified on “VEVENT”, “VTODO”, and “VJOURNAL” calendar components. RFC 7986 modifies the definition of the “UID” property to allow it to be defined in an iCalendar object. RFC 9074 adds a “UID” property to “VALARM” components to allow a unique identifier to be specified. The value of this property can then be used to refer uniquely to the “VALARM” component.

This property can be specified once only.

Security:

RFC 7986 states that UID values MUST NOT include any data that might identify a user, host, domain, or any other security- or privacy-sensitive information. It is RECOMMENDED that calendar user agents now generate “UID” values that are hex-encoded random Universally Unique Identifier (UUID) values as defined in Sections 4.4 and 4.5 of RFC 4122. You can use the uuid module to generate new UUIDs.

Compatibility:

For Alarms, X-ALARMUID is also considered.

Examples

The following is an example of such a property value: 5FC53010-1267-4F8E-BC28-1D7AE55A7C99.

Set the UID of a calendar:

>>> from icalendar import Calendar
>>> from uuid import uuid4
>>> calendar = Calendar()
>>> calendar.uid = uuid4()
>>> print(calendar.to_ical())
BEGIN:VCALENDAR
UID:d755cef5-2311-46ed-a0e1-6733c9e15c63
END:VCALENDAR
walk(name=None, select=<function Component.<lambda>>) → list[Component][source]#

Recursively traverses component and subcomponents. Returns sequence of same. If name is passed, only components with name will be returned.

Parameters:

  • name – The name of the component or None such as VEVENT.

  • select – A function that takes the component as first argument and returns True/False.

Returns:

A list of components that match.

Return type:

list[Component]

class icalendar.cal.ComponentFactory(*args, **kwargs)[source]#

Bases: CaselessDict

All components defined in RFC 5545 are registered in this factory class. To get a component you can use it like this.

class icalendar.cal.Event(*args, **kwargs)[source]#

Bases: Component

A grouping of component properties that describe an event.

Description:

A “VEVENT” calendar component is a grouping of component properties, possibly including “VALARM” calendar components, that represents a scheduled amount of time on a calendar. For example, it can be an activity; such as a one-hour long, department meeting from 8:00 AM to 9:00 AM, tomorrow. Generally, an event will take up time on an individual calendar. Hence, the event will appear as an opaque interval in a search for busy time. Alternately, the event can have its Time Transparency set to “TRANSPARENT” in order to prevent blocking of the event in searches for busy time.

The “VEVENT” is also the calendar component used to specify an anniversary or daily reminder within a calendar. These events have a DATE value type for the “DTSTART” property instead of the default value type of DATE-TIME. If such a “VEVENT” has a “DTEND” property, it MUST be specified as a DATE value also. The anniversary type of “VEVENT” can span more than one date (i.e., “DTEND” property value is set to a calendar date after the “DTSTART” property value). If such a “VEVENT” has a “DURATION” property, it MUST be specified as a “dur-day” or “dur-week” value.

The “DTSTART” property for a “VEVENT” specifies the inclusive start of the event. For recurring events, it also specifies the very first instance in the recurrence set. The “DTEND” property for a “VEVENT” calendar component specifies the non-inclusive end of the event. For cases where a “VEVENT” calendar component specifies a “DTSTART” property with a DATE value type but no “DTEND” nor “DURATION” property, the event’s duration is taken to be one day. For cases where a “VEVENT” calendar component specifies a “DTSTART” property with a DATE-TIME value type but no “DTEND” property, the event ends on the same calendar date and time of day specified by the “DTSTART” property.

The “VEVENT” calendar component cannot be nested within another calendar component. However, “VEVENT” calendar components can be related to each other or to a “VTODO” or to a “VJOURNAL” calendar component with the “RELATED-TO” property.

Examples

The following is an example of the “VEVENT” calendar component used to represent a meeting that will also be opaque to searches for busy time:

BEGIN:VEVENT
UID:19970901T130000Z-123401@example.com
DTSTAMP:19970901T130000Z
DTSTART:19970903T163000Z
DTEND:19970903T190000Z
SUMMARY:Annual Employee Review
CLASS:PRIVATE
CATEGORIES:BUSINESS,HUMAN RESOURCES
END:VEVENT

The following is an example of the “VEVENT” calendar component used to represent a reminder that will not be opaque, but rather transparent, to searches for busy time:

BEGIN:VEVENT
UID:19970901T130000Z-123402@example.com
DTSTAMP:19970901T130000Z
DTSTART:19970401T163000Z
DTEND:19970402T010000Z
SUMMARY:Laurel is in sensitivity awareness class.
CLASS:PUBLIC
CATEGORIES:BUSINESS,HUMAN RESOURCES
TRANSP:TRANSPARENT
END:VEVENT

The following is an example of the “VEVENT” calendar component used to represent an anniversary that will occur annually:

BEGIN:VEVENT
UID:19970901T130000Z-123403@example.com
DTSTAMP:19970901T130000Z
DTSTART;VALUE=DATE:19971102
SUMMARY:Our Blissful Anniversary
TRANSP:TRANSPARENT
CLASS:CONFIDENTIAL
CATEGORIES:ANNIVERSARY,PERSONAL,SPECIAL OCCASION
RRULE:FREQ=YEARLY
END:VEVENT

The following is an example of the “VEVENT” calendar component used to represent a multi-day event scheduled from June 28th, 2007 to July 8th, 2007 inclusively. Note that the “DTEND” property is set to July 9th, 2007, since the “DTEND” property specifies the non-inclusive end of the event.

BEGIN:VEVENT
UID:20070423T123432Z-541111@example.com
DTSTAMP:20070423T123432Z
DTSTART;VALUE=DATE:20070628
DTEND;VALUE=DATE:20070709
SUMMARY:Festival International de Jazz de Montreal
TRANSP:TRANSPARENT
END:VEVENT

Create a new Event:

>>> from icalendar import Event
>>> from datetime import datetime
>>> event = Event.new(start=datetime(2021, 1, 1, 12, 30, 0))
>>> print(event.to_ical())
BEGIN:VEVENT
DTSTART:20210101T123000
DTSTAMP:20250517T080612Z
UID:d755cef5-2311-46ed-a0e1-6733c9e15c63
END:VEVENT
property DTEND: date | None#

The DTEND property.

The “DTEND” property for a “VEVENT” calendar component specifies the non-inclusive end of the event.

Accepted values: datetime, date. If the attribute has invalid values, we raise InvalidCalendar. If the value is absent, we return None. You can also delete the value with del or by setting it to None.

property DTSTART: date | None#

The DTSTART property.

The “DTSTART” property for a “VEVENT” specifies the inclusive start of the event.

Accepted values: datetime, date. If the attribute has invalid values, we raise InvalidCalendar. If the value is absent, we return None. You can also delete the value with del or by setting it to None.

property DURATION: timedelta | None#

The DURATION property.

The “DTSTART” property for a “VEVENT” specifies the inclusive start of the VEVENT. The “DURATION” property in conjunction with the DTSTART property for a “VEVENT” calendar component specifies the non-inclusive end of the event.

If you would like to calculate the duration of a VEVENT, do not use this. Instead use the duration property (lower case).

property X_MOZ_LASTACK: datetime | None#

The X-MOZ-LASTACK property. datetime in UTC

All values will be converted to a datetime in UTC. Thunderbird: Alarms before this time are acknowledged.

property X_MOZ_SNOOZE_TIME: datetime | None#

The X-MOZ-SNOOZE-TIME property. datetime in UTC

All values will be converted to a datetime in UTC. Thunderbird: Alarms before this time are snoozed.

property alarms: Alarms#

Compute the alarm times for this component.

>>> from icalendar import Event
>>> event = Event.example("rfc_9074_example_1")
>>> len(event.alarms.times)
1
>>> alarm_time = event.alarms.times[0]
>>> alarm_time.trigger  # The time when the alarm pops up
datetime.datetime(2021, 3, 2, 10, 15, tzinfo=ZoneInfo(key='America/New_York'))
>>> alarm_time.is_active()  # This alarm has not been acknowledged
True

Note that this only uses DTSTART and DTEND, but ignores RDATE, EXDATE, and RRULE properties.

property attendees: list[vCalAddress]#

ATTENDEE defines one or more “Attendees” within a calendar component.

Conformance:

This property MUST be specified in an iCalendar object that specifies a group-scheduled calendar entity. This property MUST NOT be specified in an iCalendar object when publishing the calendar information (e.g., NOT in an iCalendar object that specifies the publication of a calendar user’s busy time, event, to-do, or journal). This property is not specified in an iCalendar object that specifies only a time zone definition or that defines calendar components that are not group-scheduled components, but are components only on a single user’s calendar.

Description:

This property MUST only be specified within calendar components to specify participants, non-participants, and the chair of a group-scheduled calendar entity. The property is specified within an “EMAIL” category of the “VALARM” calendar component to specify an email address that is to receive the email type of iCalendar alarm.

Examples

Add a new attendee to an existing event.

>>> from icalendar import Event, vCalAddress
>>> event = Event()
>>> event.attendees.append(vCalAddress("mailto:me@my-domain.com"))
>>> print(event.to_ical())
BEGIN:VEVENT
ATTENDEE:mailto:me@my-domain.com
END:VEVENT

Create an email alarm with several attendees:

>>> from icalendar import Alarm, vCalAddress
>>> alarm = Alarm.new(attendees = [
...     vCalAddress("mailto:me@my-domain.com"),
...     vCalAddress("mailto:you@my-domain.com"),
... ], summary = "Email alarm")
>>> print(alarm.to_ical())
BEGIN:VALARM
ATTENDEE:mailto:me@my-domain.com
ATTENDEE:mailto:you@my-domain.com
SUMMARY:Email alarm
END:VALARM
canonical_order = ('SUMMARY', 'DTSTART', 'DTEND', 'DURATION', 'DTSTAMP', 'UID', 'RECURRENCE-ID', 'SEQUENCE', 'RRULE', 'RDATE', 'EXDATE')#
property categories: list[str]#

This property defines the categories for a component.

Property Parameters:

IANA, non-standard, and language property parameters can be specified on this property.

Conformance:

The property can be specified within “VEVENT”, “VTODO”, or “VJOURNAL” calendar components. Since RFC 7986 it can also be defined on a “VCALENDAR” component.

Description:

This property is used to specify categories or subtypes of the calendar component. The categories are useful in searching for a calendar component of a particular type and category. Within the “VEVENT”, “VTODO”, or “VJOURNAL” calendar components, more than one category can be specified as a COMMA-separated list of categories.

Example

Below, we add the categories to an event:

>>> from icalendar import Event
>>> event = Event()
>>> event.categories = ["Work", "Meeting"]
>>> print(event.to_ical())
BEGIN:VEVENT
CATEGORIES:Work,Meeting
END:VEVENT
>>> event.categories.append("Lecture")
>>> event.categories == ["Work", "Meeting", "Lecture"]
True

Note

At present, we do not take the LANGUAGE parameter into account.

property classification: StrEnum#

CLASS specifies the class of the calendar component.

Returns:

icalendar.enums.CLASS

Description:

An access classification is only one component of the general security system within a calendar application. It provides a method of capturing the scope of the access the calendar owner intends for information within an individual calendar entry. The access classification of an individual iCalendar component is useful when measured along with the other security components of a calendar system (e.g., calendar user authentication, authorization, access rights, access role, etc.). Hence, the semantics of the individual access classifications cannot be completely defined by this memo alone. Additionally, due to the “blind” nature of most exchange processes using this memo, these access classifications cannot serve as an enforcement statement for a system receiving an iCalendar object. Rather, they provide a method for capturing the intention of the calendar owner for the access to the calendar component. If not specified in a component that allows this property, the default value is PUBLIC. Applications MUST treat x-name and iana-token values they don’t recognize the same way as they would the PRIVATE value.

property color: str#

This property specifies a color used for displaying the component.

This implements RFC 7986 COLOR property.

Property Parameters:

IANA and non-standard property parameters can be specified on this property.

Conformance:

This property can be specified once in an iCalendar object or in VEVENT, VTODO, or VJOURNAL calendar components.

Description:

This property specifies a color that clients MAY use when presenting the relevant data to a user. Typically, this would appear as the “background” color of events or tasks. The value is a case-insensitive color name taken from the CSS3 set of names, defined in Section 4.3 of W3C.REC-css3-color-20110607.

Example

"turquoise", "#ffffff"

>>> from icalendar import Todo
>>> todo = Todo()
>>> todo.color = "green"
>>> print(todo.to_ical())
BEGIN:VTODO
COLOR:green
END:VTODO
property conferences: list[Conference]#

Return the CONFERENCE properties as a list.

Purpose:

This property specifies information for accessing a conferencing system.

Conformance:

This property can be specified multiple times in a “VEVENT” or “VTODO” calendar component.

Description:

This property specifies information for accessing a conferencing system for attendees of a meeting or task. This might be for a telephone-based conference number dial-in with access codes included (such as a tel: URI RFC 3966 or a sip: or sips: URI RFC 3261), for a web-based video chat (such as an http: or https: URI RFC 7230), or for an instant messaging group chat room (such as an xmpp: URI RFC 5122). If a specific URI for a conferencing system is not available, a data: URI RFC 2397 containing a text description can be used.

A conference system can be a bidirectional communication channel or a uni-directional “broadcast feed”.

The “FEATURE” property parameter is used to describe the key capabilities of the conference system to allow a client to choose the ones that give the required level of interaction from a set of multiple properties.

The “LABEL” property parameter is used to convey additional details on the use of the URI. For example, the URIs or access codes for the moderator and attendee of a teleconference system could be different, and the “LABEL” property parameter could be used to “tag” each “CONFERENCE” property to indicate which is which.

The “LANGUAGE” property parameter can be used to specify the language used for text values used with this property (as per Section 3.2.10 of RFC 5545).

Example

The following are examples of this property:

CONFERENCE;VALUE=URI;FEATURE=PHONE,MODERATOR;
 LABEL=Moderator dial-in:tel:+1-412-555-0123,,,654321
CONFERENCE;VALUE=URI;FEATURE=PHONE;
 LABEL=Attendee dial-in:tel:+1-412-555-0123,,,555123
CONFERENCE;VALUE=URI;FEATURE=PHONE;
 LABEL=Attendee dial-in:tel:+1-888-555-0456,,,555123
CONFERENCE;VALUE=URI;FEATURE=CHAT;
 LABEL=Chat room:xmpp:chat-123@conference.example.com
CONFERENCE;VALUE=URI;FEATURE=AUDIO,VIDEO;
 LABEL=Attendee dial-in:https://chat.example.com/audio?id=123456

Get all conferences:

>>> from icalendar import Event
>>> event = Event()
>>> event.conferences
[]

Set a conference:

>>> from icalendar import Event, Conference
>>> event = Event()
>>> event.conferences = [
...     Conference(
...         "tel:+1-412-555-0123,,,654321",
...         feature="PHONE,MODERATOR",
...         label="Moderator dial-in",
...         language="EN",
...     )
... ]
>>> print(event.to_ical())
BEGIN:VEVENT
CONFERENCE;FEATURE="PHONE,MODERATOR";LABEL=Moderator dial-in;LANGUAGE=EN:t
 el:+1-412-555-0123,,,654321
END:VEVENT
property contacts: list[str]#

Contact information associated with the calendar component.

Purpose:

This property is used to represent contact information or alternately a reference to contact information associated with the calendar component.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

In RFC 5545, this property can be specified in a “VEVENT”, “VTODO”, “VJOURNAL”, or “VFREEBUSY” calendar component. In RFC 7953, this property can be specified in a “VAVAILABILITY” amd “VAVAILABLE” calendar component.

Description:

The property value consists of textual contact information. An alternative representation for the property value can also be specified that refers to a URI pointing to an alternate form, such as a vCard RFC 2426, for the contact information.

Example

The following is an example of this property referencing textual contact information:

CONTACT:Jim Dolittle\, ABC Industries\, +1-919-555-1234

The following is an example of this property with an alternate representation of an LDAP URI to a directory entry containing the contact information:

CONTACT;ALTREP="ldap://example.com:6666/o=ABC%20Industries\,
c=US???(cn=Jim%20Dolittle)":Jim Dolittle\, ABC Industries\,
+1-919-555-1234

The following is an example of this property with an alternate representation of a MIME body part containing the contact information, such as a vCard RFC 2426 embedded in a text/ directory media type RFC 2425:

CONTACT;ALTREP="CID:part3.msg970930T083000SILVER@example.com":
 Jim Dolittle\, ABC Industries\, +1-919-555-1234

The following is an example of this property referencing a network resource, such as a vCard RFC 2426 object containing the contact information:

CONTACT;ALTREP="http://example.com/pdi/jdoe.vcf":Jim
 Dolittle\, ABC Industries\, +1-919-555-1234
property description: str | None#

DESCRIPTION provides a more complete description of the calendar component than that provided by the “SUMMARY” property.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

The property can be specified in the “VEVENT”, “VTODO”, “VJOURNAL”, or “VALARM” calendar components. The property can be specified multiple times only within a “VJOURNAL” calendar component.

Description:

This property is used in the “VEVENT” and “VTODO” to capture lengthy textual descriptions associated with the activity.

This property is used in the “VALARM” calendar component to capture the display text for a DISPLAY category of alarm, and to capture the body text for an EMAIL category of alarm.

Examples

The following is an example of this property with formatted line breaks in the property value:

DESCRIPTION:Meeting to provide technical review for "Phoenix"
 design.\nHappy Face Conference Room. Phoenix design team
 MUST attend this meeting.\nRSVP to team leader.
property duration: timedelta#

The duration of the VEVENT.

Returns the DURATION property if set, otherwise calculated from start and end. When setting duration, the end time is automatically calculated from start + duration. You can set the duration to automatically adjust the end time while keeping start locked.

Setting the duration will: 1. Keep the start time locked (unchanged) 2. Adjust the end time to start + duration 3. Remove any existing DTEND property 4. Set the DURATION property

property end: date | datetime#

The end of the event.

Invalid values raise an InvalidCalendar error. If there is no end, we also raise an IncompleteComponent error.

classmethod example(name: str = 'rfc_9074_example_3') → Event[source]#

Return the calendar example with the given name.

exclusive = ('DTEND', 'DURATION')#
property exdates: list[date | datetime]#

EXDATE defines the list of DATE-TIME exceptions for recurring components.

EXDATE is defined in RFC 5545.

Value Type:

The default value type for this property is DATE-TIME. The value type can be set to DATE.

Property Parameters:

IANA, non-standard, value data type, and time zone identifier property parameters can be specified on this property.

Conformance:

This property can be specified in recurring “VEVENT”, “VTODO”, and “VJOURNAL” calendar components as well as in the “STANDARD” and “DAYLIGHT” sub-components of the “VTIMEZONE” calendar component.

Description:

The exception dates, if specified, are used in computing the recurrence set. The recurrence set is the complete set of recurrence instances for a calendar component. The recurrence set is generated by considering the initial “DTSTART” property along with the “RRULE”, “RDATE”, and “EXDATE” properties contained within the recurring component. The “DTSTART” property defines the first instance in the recurrence set. The “DTSTART” property value SHOULD match the pattern of the recurrence rule, if specified. The recurrence set generated with a “DTSTART” property value that doesn’t match the pattern of the rule is undefined. The final recurrence set is generated by gathering all of the start DATE-TIME values generated by any of the specified “RRULE” and “RDATE” properties, and then excluding any start DATE-TIME values specified by “EXDATE” properties. This implies that start DATE-TIME values specified by “EXDATE” properties take precedence over those specified by inclusion properties (i.e., “RDATE” and “RRULE”). When duplicate instances are generated by the “RRULE” and “RDATE” properties, only one recurrence is considered. Duplicate instances are ignored.

The “EXDATE” property can be used to exclude the value specified in “DTSTART”. However, in such cases, the original “DTSTART” date MUST still be maintained by the calendaring and scheduling system because the original “DTSTART” value has inherent usage dependencies by other properties such as the “RECURRENCE-ID”.

Example

Below, we add an exdate in a list and get the resulting list of exdates.

>>> from icalendar import Event
>>> from datetime import datetime
>>> event = Event()

# Add a list of excluded dates
>>> event.add("EXDATE", [datetime(2025, 4, 28, 16, 5)])
>>> event.exdates
[datetime.datetime(2025, 4, 28, 16, 5)]

Note

You cannot modify the EXDATE value by modifying the result. Use icalendar.cal.Component.add() to add values.

If you want to compute recurrences, have a look at Related projects.

ignore_exceptions = True#
property images: list[Image]#

IMAGE specifies an image associated with the calendar or a calendar component.

Description:

This property specifies an image for an iCalendar object or a calendar component via a URI or directly with inline data that can be used by calendar user agents when presenting the calendar data to a user. Multiple properties MAY be used to specify alternative sets of images with, for example, varying media subtypes, resolutions, or sizes. When multiple properties are present, calendar user agents SHOULD display only one of them, picking one that provides the most appropriate image quality, or display none. The “DISPLAY” parameter is used to indicate the intended display mode for the image. The “ALTREP” parameter, defined in RFC 5545, can be used to provide a “clickable” image where the URI in the parameter value can be “launched” by a click on the image in the calendar user agent.

Conformance:

This property can be specified multiple times in an iCalendar object or in “VEVENT”, “VTODO”, or “VJOURNAL” calendar components.

Note

At the present moment, this property is read-only. If you require a setter, please open an issue or a pull request.

property location: str | None#

The intended venue for the activity defined by a calendar component.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

Since RFC 5545, this property can be specified in “VEVENT” or “VTODO” calendar component. RFC 7953 adds this property to “VAVAILABILITY” and “VAVAILABLE”.

Description:

Specific venues such as conference or meeting rooms may be explicitly specified using this property. An alternate representation may be specified that is a URI that points to directory information with more structured specification of the location. For example, the alternate representation may specify either an LDAP URL RFC 4516 pointing to an LDAP server entry or a CID URL RFC 2392 pointing to a MIME body part containing a Virtual-Information Card (vCard) RFC 2426 for the location.

multiple = ('ATTACH', 'ATTENDEE', 'CATEGORIES', 'COMMENT', 'CONTACT', 'EXDATE', 'RSTATUS', 'RELATED', 'RESOURCES', 'RDATE', 'RRULE')#
name = 'VEVENT'#
classmethod new(attendees: list[vCalAddress] | None = None, categories: Sequence[str] = (), classification: CLASS | None = None, color: str | None = None, comments: list[str] | str | None = None, conferences: list[Conference] | None = None, contacts: list[str] | str | None = None, created: date | None = None, description: str | None = None, end: date | datetime | None = None, last_modified: date | None = None, location: str | None = None, organizer: vCalAddress | str | None = None, priority: int | None = None, sequence: int | None = None, stamp: date | None = None, start: date | datetime | None = None, status: STATUS | None = None, transparency: TRANSP | None = None, summary: str | None = None, uid: str | uuid.UUID | None = None, url: str | None = None)[source]#

Create a new event with all required properties.

This creates a new Event in accordance with RFC 5545.

Parameters:
Returns:

Event

Raises:

InvalidCalendar – If the content is not valid according to RFC 5545.

Warning

As time progresses, we will be stricter with the validation.

property organizer: vCalAddress | None#

ORGANIZER defines the organizer for a calendar component.

Property Parameters:

IANA, non-standard, language, common name, directory entry reference, and sent-by property parameters can be specified on this property.

Conformance:

This property MUST be specified in an iCalendar object that specifies a group-scheduled calendar entity. This property MUST be specified in an iCalendar object that specifies the publication of a calendar user’s busy time. This property MUST NOT be specified in an iCalendar object that specifies only a time zone definition or that defines calendar components that are not group-scheduled components, but are components only on a single user’s calendar.

Description:

This property is specified within the “VEVENT”, “VTODO”, and “VJOURNAL” calendar components to specify the organizer of a group-scheduled calendar entity. The property is specified within the “VFREEBUSY” calendar component to specify the calendar user requesting the free or busy time. When publishing a “VFREEBUSY” calendar component, the property is used to specify the calendar that the published busy time came from.

The property has the property parameters “CN”, for specifying the common or display name associated with the “Organizer”, “DIR”, for specifying a pointer to the directory information associated with the “Organizer”, “SENT-BY”, for specifying another calendar user that is acting on behalf of the “Organizer”. The non-standard parameters may also be specified on this property. If the “LANGUAGE” property parameter is specified, the identified language applies to the “CN” parameter value.

property priority: int#
Conformance:

This property can be specified in “VEVENT” and “VTODO” calendar components according to RFC 5545. RFC 7953 adds this property to “VAVAILABILITY”.

Description:

This priority is specified as an integer in the range 0 to 9. A value of 0 specifies an undefined priority. A value of 1 is the highest priority. A value of 2 is the second highest priority. Subsequent numbers specify a decreasing ordinal priority. A value of 9 is the lowest priority.

A CUA with a three-level priority scheme of “HIGH”, “MEDIUM”, and “LOW” is mapped into this property such that a property value in the range of 1 to 4 specifies “HIGH” priority. A value of 5 is the normal or “MEDIUM” priority. A value in the range of 6 to 9 is “LOW” priority.

A CUA with a priority schema of “A1”, “A2”, “A3”, “B1”, “B2”, …, “C3” is mapped into this property such that a property value of 1 specifies “A1”, a property value of 2 specifies “A2”, a property value of 3 specifies “A3”, and so forth up to a property value of 9 specifies “C3”.

Other integer values are reserved for future use.

Within a “VEVENT” calendar component, this property specifies a priority for the event. This property may be useful when more than one event is scheduled for a given time period.

Within a “VTODO” calendar component, this property specified a priority for the to-do. This property is useful in prioritizing multiple action items for a given time period.

property rdates: list[tuple[date, None] | tuple[datetime, None] | tuple[datetime, datetime]]#

The RDATE property defines the list of DATE-TIME values for recurring components.

RDATE is defined in RFC 5545. The return value is a list of tuples (start, end).

start can be a datetime.date or a datetime.datetime, with and without timezone.

end is None if the end is not specified and a datetime.datetime if the end is specified.

Value Type:

The default value type for this property is DATE-TIME. The value type can be set to DATE or PERIOD.

Property Parameters:

IANA, non-standard, value data type, and time zone identifier property parameters can be specified on this property.

Conformance:

This property can be specified in recurring “VEVENT”, “VTODO”, and “VJOURNAL” calendar components as well as in the “STANDARD” and “DAYLIGHT” sub-components of the “VTIMEZONE” calendar component.

Description:

This property can appear along with the “RRULE” property to define an aggregate set of repeating occurrences. When they both appear in a recurring component, the recurrence instances are defined by the union of occurrences defined by both the “RDATE” and “RRULE”.

The recurrence dates, if specified, are used in computing the recurrence set. The recurrence set is the complete set of recurrence instances for a calendar component. The recurrence set is generated by considering the initial “DTSTART” property along with the “RRULE”, “RDATE”, and “EXDATE” properties contained within the recurring component. The “DTSTART” property defines the first instance in the recurrence set. The “DTSTART” property value SHOULD match the pattern of the recurrence rule, if specified. The recurrence set generated with a “DTSTART” property value that doesn’t match the pattern of the rule is undefined. The final recurrence set is generated by gathering all of the start DATE-TIME values generated by any of the specified “RRULE” and “RDATE” properties, and then excluding any start DATE-TIME values specified by “EXDATE” properties. This implies that start DATE-TIME values specified by “EXDATE” properties take precedence over those specified by inclusion properties (i.e., “RDATE” and “RRULE”). Where duplicate instances are generated by the “RRULE” and “RDATE” properties, only one recurrence is considered. Duplicate instances are ignored.

Example

Below, we set one RDATE in a list and get the resulting tuple of start and end.

>>> from icalendar import Event
>>> from datetime import datetime
>>> event = Event()

# Add a list of recurrence dates
>>> event.add("RDATE", [datetime(2025, 4, 28, 16, 5)])
>>> event.rdates
[(datetime.datetime(2025, 4, 28, 16, 5), None)]

Note

You cannot modify the RDATE value by modifying the result. Use icalendar.cal.Component.add() to add values.

If you want to compute recurrences, have a look at Related projects.

required = ('UID', 'DTSTAMP')#
property rrules: list[vRecur]#

RRULE defines a rule or repeating pattern for recurring components.

RRULE is defined in RFC 5545. RFC 7529 adds the SKIP parameter icalendar.prop.vSkip.

Property Parameters:

IANA and non-standard property parameters can be specified on this property.

Conformance:

This property can be specified in recurring “VEVENT”, “VTODO”, and “VJOURNAL” calendar components as well as in the “STANDARD” and “DAYLIGHT” sub-components of the “VTIMEZONE” calendar component, but it SHOULD NOT be specified more than once. The recurrence set generated with multiple “RRULE” properties is undefined.

Description:

The recurrence rule, if specified, is used in computing the recurrence set. The recurrence set is the complete set of recurrence instances for a calendar component. The recurrence set is generated by considering the initial “DTSTART” property along with the “RRULE”, “RDATE”, and “EXDATE” properties contained within the recurring component. The “DTSTART” property defines the first instance in the recurrence set. The “DTSTART” property value SHOULD be synchronized with the recurrence rule, if specified. The recurrence set generated with a “DTSTART” property value not synchronized with the recurrence rule is undefined. The final recurrence set is generated by gathering all of the start DATE-TIME values generated by any of the specified “RRULE” and “RDATE” properties, and then excluding any start DATE-TIME values specified by “EXDATE” properties. This implies that start DATE- TIME values specified by “EXDATE” properties take precedence over those specified by inclusion properties (i.e., “RDATE” and “RRULE”). Where duplicate instances are generated by the “RRULE” and “RDATE” properties, only one recurrence is considered. Duplicate instances are ignored.

The “DTSTART” property specified within the iCalendar object defines the first instance of the recurrence. In most cases, a “DTSTART” property of DATE-TIME value type used with a recurrence rule, should be specified as a date with local time and time zone reference to make sure all the recurrence instances start at the same local time regardless of time zone changes.

If the duration of the recurring component is specified with the “DTEND” or “DUE” property, then the same exact duration will apply to all the members of the generated recurrence set. Else, if the duration of the recurring component is specified with the “DURATION” property, then the same nominal duration will apply to all the members of the generated recurrence set and the exact duration of each recurrence instance will depend on its specific start time. For example, recurrence instances of a nominal duration of one day will have an exact duration of more or less than 24 hours on a day where a time zone shift occurs. The duration of a specific recurrence may be modified in an exception component or simply by using an “RDATE” property of PERIOD value type.

Examples

Daily for 10 occurrences:

>>> from icalendar import Event
>>> from datetime import datetime
>>> from zoneinfo import ZoneInfo
>>> event = Event()
>>> event.start = datetime(1997, 9, 2, 9, 0, tzinfo=ZoneInfo("America/New_York"))
>>> event.add("RRULE", "FREQ=DAILY;COUNT=10")
>>> print(event.to_ical())
BEGIN:VEVENT
DTSTART;TZID=America/New_York:19970902T090000
RRULE:FREQ=DAILY;COUNT=10
END:VEVENT
>>> event.rrules
[vRecur({'FREQ': ['DAILY'], 'COUNT': [10]})]

Daily until December 24, 1997:

>>> from icalendar import Event, vRecur
>>> from datetime import datetime
>>> from zoneinfo import ZoneInfo
>>> event = Event()
>>> event.start = datetime(1997, 9, 2, 9, 0, tzinfo=ZoneInfo("America/New_York"))
>>> event.add("RRULE", vRecur({"FREQ": ["DAILY"]}, until=datetime(1997, 12, 24, tzinfo=ZoneInfo("UTC"))))
>>> print(event.to_ical())
BEGIN:VEVENT
DTSTART;TZID=America/New_York:19970902T090000
RRULE:FREQ=DAILY;UNTIL=19971224T000000Z
END:VEVENT
>>> event.rrules
[vRecur({'FREQ': ['DAILY'], 'UNTIL': [datetime.datetime(1997, 12, 24, 0, 0, tzinfo=ZoneInfo(key='UTC'))]})]

Note

You cannot modify the RRULE value by modifying the result. Use icalendar.cal.Component.add() to add values.

If you want to compute recurrences, have a look at Related projects.

property sequence: int#

This property defines the revision sequence number of the calendar component within a sequence of revisions.

Value Type:

INTEGER

Property Parameters:

IANA and non-standard property parameters can be specified on this property.

Conformance:

The property can be specified in “VEVENT”, “VTODO”, or “VJOURNAL” calendar component.

Description:

When a calendar component is created, its sequence number is 0. It is monotonically incremented by the “Organizer’s” CUA each time the “Organizer” makes a significant revision to the calendar component.

The “Organizer” includes this property in an iCalendar object that it sends to an “Attendee” to specify the current version of the calendar component.

The “Attendee” includes this property in an iCalendar object that it sends to the “Organizer” to specify the version of the calendar component to which the “Attendee” is referring.

A change to the sequence number is not the mechanism that an “Organizer” uses to request a response from the “Attendees”. The “RSVP” parameter on the “ATTENDEE” property is used by the “Organizer” to indicate that a response from the “Attendees” is requested.

Recurrence instances of a recurring component MAY have different sequence numbers.

Examples

The following is an example of this property for a calendar component that was just created by the “Organizer”:

>>> from icalendar import Event
>>> event = Event()
>>> event.sequence
0

The following is an example of this property for a calendar component that has been revised 10 different times by the “Organizer”:

>>> from icalendar import Calendar
>>> calendar = Calendar.example("issue_156_RDATE_with_PERIOD_TZID_khal")
>>> event = calendar.events[0]
>>> event.sequence
10
set_duration(duration: timedelta | None, locked: Literal['start', 'end'] = 'start')[source]#

Set the duration of the event relative to either start or end.

Parameters:

  • duration – The duration to set, or None to convert to DURATION property

  • locked – Which property to keep unchanged (‘start’ or ‘end’)

set_end(end: date | datetime, locked: Literal['start', 'duration'] = 'start')[source]#

Set the end of the component, keeping either the start or the duration same.

Parameters:

  • end – The end time to set

  • locked – Which property to keep unchanged (‘start’ or ‘duration’)

set_start(start: date | datetime, locked: Literal['duration', 'end'] | None = None)[source]#

Set the start and keep the duration or end of the event.

Parameters:

  • start – The start time to set

  • locked – Which property to keep unchanged (‘duration’, ‘end’, or None for auto-detect)

singletons = ('CLASS', 'CREATED', 'COLOR', 'DESCRIPTION', 'DTSTART', 'GEO', 'LAST-MODIFIED', 'LOCATION', 'ORGANIZER', 'PRIORITY', 'DTSTAMP', 'SEQUENCE', 'STATUS', 'SUMMARY', 'TRANSP', 'URL', 'RECURRENCE-ID', 'DTEND', 'DURATION', 'UID')#
property start: date | datetime#

The start of the event.

Invalid values raise an InvalidCalendar. If there is no start, we also raise an IncompleteComponent error.

You can get the start, end and duration of an event as follows:

>>> from datetime import datetime
>>> from icalendar import Event
>>> event = Event()
>>> event.start = datetime(2021, 1, 1, 12)
>>> event.end = datetime(2021, 1, 1, 12, 30) # 30 minutes
>>> event.duration  # 1800 seconds == 30 minutes
datetime.timedelta(seconds=1800)
>>> print(event.to_ical())
BEGIN:VEVENT
DTSTART:20210101T120000
DTEND:20210101T123000
END:VEVENT
property status: StrEnum#

STATUS defines the overall status or confirmation for the calendar component.

Returns:

icalendar.enums.STATUS

The default value is "".

Description:

In a group-scheduled calendar component, the property is used by the “Organizer” to provide a confirmation of the event to the “Attendees”. For example in a “VEVENT” calendar component, the “Organizer” can indicate that a meeting is tentative, confirmed, or cancelled. In a “VTODO” calendar component, the “Organizer” can indicate that an action item needs action, is completed, is in process or being worked on, or has been cancelled. In a “VJOURNAL” calendar component, the “Organizer” can indicate that a journal entry is draft, final, or has been cancelled or removed.

subcomponents: list[Component]#
property summary: str | None#

SUMMARY defines a short summary or subject for the calendar component.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

The property can be specified in “VEVENT”, “VTODO”, “VJOURNAL”, or “VALARM” calendar components.

Description:

This property is used in the “VEVENT”, “VTODO”, and “VJOURNAL” calendar components to capture a short, one-line summary about the activity or journal entry.

This property is used in the “VALARM” calendar component to capture the subject of an EMAIL category of alarm.

Examples

The following is an example of this property:

SUMMARY:Department Party
property transparency: StrEnum#

TRANSP defines whether or not an event is transparent to busy time searches.

Returns:

icalendar.enums.TRANSP

Description:

Time Transparency is the characteristic of an event that determines whether it appears to consume time on a calendar. Events that consume actual time for the individual or resource associated with the calendar SHOULD be recorded as OPAQUE, allowing them to be detected by free/busy time searches. Other events, which do not take up the individual’s (or resource’s) time SHOULD be recorded as TRANSPARENT, making them invisible to free/ busy time searches.

property uid: str#

UID specifies the persistent, globally unique identifier for a component.

We recommend using uuid.uuid4() to generate new values.

Returns:

The value of the UID property as a string or "" if no value is set.

Description:

The “UID” itself MUST be a globally unique identifier. The generator of the identifier MUST guarantee that the identifier is unique.

This is the method for correlating scheduling messages with the referenced “VEVENT”, “VTODO”, or “VJOURNAL” calendar component. The full range of calendar components specified by a recurrence set is referenced by referring to just the “UID” property value corresponding to the calendar component. The “RECURRENCE-ID” property allows the reference to an individual instance within the recurrence set.

This property is an important method for group-scheduling applications to match requests with later replies, modifications, or deletion requests. Calendaring and scheduling applications MUST generate this property in “VEVENT”, “VTODO”, and “VJOURNAL” calendar components to assure interoperability with other group- scheduling applications. This identifier is created by the calendar system that generates an iCalendar object.

Implementations MUST be able to receive and persist values of at least 255 octets for this property, but they MUST NOT truncate values in the middle of a UTF-8 multi-octet sequence.

RFC 7986 states that UID can be used, for example, to identify duplicate calendar streams that a client may have been given access to. It can be used in conjunction with the “LAST-MODIFIED” property also specified on the “VCALENDAR” object to identify the most recent version of a calendar.

Conformance:

RFC 5545 states that the “UID” property can be specified on “VEVENT”, “VTODO”, and “VJOURNAL” calendar components. RFC 7986 modifies the definition of the “UID” property to allow it to be defined in an iCalendar object. RFC 9074 adds a “UID” property to “VALARM” components to allow a unique identifier to be specified. The value of this property can then be used to refer uniquely to the “VALARM” component.

This property can be specified once only.

Security:

RFC 7986 states that UID values MUST NOT include any data that might identify a user, host, domain, or any other security- or privacy-sensitive information. It is RECOMMENDED that calendar user agents now generate “UID” values that are hex-encoded random Universally Unique Identifier (UUID) values as defined in Sections 4.4 and 4.5 of RFC 4122. You can use the uuid module to generate new UUIDs.

Compatibility:

For Alarms, X-ALARMUID is also considered.

Examples

The following is an example of such a property value: 5FC53010-1267-4F8E-BC28-1D7AE55A7C99.

Set the UID of a calendar:

>>> from icalendar import Calendar
>>> from uuid import uuid4
>>> calendar = Calendar()
>>> calendar.uid = uuid4()
>>> print(calendar.to_ical())
BEGIN:VCALENDAR
UID:d755cef5-2311-46ed-a0e1-6733c9e15c63
END:VCALENDAR
property url: str#

A Uniform Resource Locator (URL) associated with the iCalendar object.

Description:

This property may be used in a calendar component to convey a location where a more dynamic rendition of the calendar information associated with the calendar component can be found. This memo does not attempt to standardize the form of the URI, nor the format of the resource pointed to by the property value. If the URL property and Content-Location MIME header are both specified, they MUST point to the same resource.

Conformance:

This property can be specified once in the “VEVENT”, “VTODO”, “VJOURNAL”, or “VFREEBUSY” calendar components. Since RFC 7986, this property can also be defined on a “VCALENDAR”.

Example

The following is an example of this property:

URL:http://example.com/pub/calendars/jsmith/mytime.ics
class icalendar.cal.FreeBusy(*args, **kwargs)[source]#

Bases: Component

A “VFREEBUSY” calendar component is a grouping of component properties that represents either a request for free or busy time information, a reply to a request for free or busy time information, or a published set of busy time information.

Examples

Create a new FreeBusy:

>>> from icalendar import FreeBusy
>>> free_busy = FreeBusy.new()
>>> print(free_busy.to_ical())
BEGIN:VFREEBUSY
DTSTAMP:20250517T080612Z
UID:d755cef5-2311-46ed-a0e1-6733c9e15c63
END:VFREEBUSY
property DTEND: date | None#

The DTEND property.

The “DTEND” property for a “VFREEBUSY” calendar component specifies the non-inclusive end of the component.

Accepted values: datetime, date. If the attribute has invalid values, we raise InvalidCalendar. If the value is absent, we return None. You can also delete the value with del or by setting it to None.

property DTSTART: date | None#

The DTSTART property.

The “DTSTART” property for a “VFREEBUSY” specifies the inclusive start of the component.

Accepted values: datetime, date. If the attribute has invalid values, we raise InvalidCalendar. If the value is absent, we return None. You can also delete the value with del or by setting it to None.

property contacts: list[str]#

Contact information associated with the calendar component.

Purpose:

This property is used to represent contact information or alternately a reference to contact information associated with the calendar component.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

In RFC 5545, this property can be specified in a “VEVENT”, “VTODO”, “VJOURNAL”, or “VFREEBUSY” calendar component. In RFC 7953, this property can be specified in a “VAVAILABILITY” amd “VAVAILABLE” calendar component.

Description:

The property value consists of textual contact information. An alternative representation for the property value can also be specified that refers to a URI pointing to an alternate form, such as a vCard RFC 2426, for the contact information.

Example

The following is an example of this property referencing textual contact information:

CONTACT:Jim Dolittle\, ABC Industries\, +1-919-555-1234

The following is an example of this property with an alternate representation of an LDAP URI to a directory entry containing the contact information:

CONTACT;ALTREP="ldap://example.com:6666/o=ABC%20Industries\,
c=US???(cn=Jim%20Dolittle)":Jim Dolittle\, ABC Industries\,
+1-919-555-1234

The following is an example of this property with an alternate representation of a MIME body part containing the contact information, such as a vCard RFC 2426 embedded in a text/ directory media type RFC 2425:

CONTACT;ALTREP="CID:part3.msg970930T083000SILVER@example.com":
 Jim Dolittle\, ABC Industries\, +1-919-555-1234

The following is an example of this property referencing a network resource, such as a vCard RFC 2426 object containing the contact information:

CONTACT;ALTREP="http://example.com/pdi/jdoe.vcf":Jim
 Dolittle\, ABC Industries\, +1-919-555-1234
property duration: timedelta | None#

The duration computed from start and end.

property end: date | None#

The DTEND property.

The “DTEND” property for a “VFREEBUSY” calendar component specifies the non-inclusive end of the component.

Accepted values: datetime, date. If the attribute has invalid values, we raise InvalidCalendar. If the value is absent, we return None. You can also delete the value with del or by setting it to None.

multiple = ('ATTENDEE', 'COMMENT', 'FREEBUSY', 'RSTATUS')#
name = 'VFREEBUSY'#
classmethod new(comments: list[str] | str | None = None, contacts: list[str] | str | None = None, end: date | datetime | None = None, organizer: vCalAddress | str | None = None, stamp: date | None = None, start: date | datetime | None = None, uid: str | uuid.UUID | None = None, url: str | None = None)[source]#

Create a new alarm with all required properties.

This creates a new Alarm in accordance with RFC 5545.

Parameters:

  • comments – The Component.comments of the component.

  • organizer – The organizer of the component.

  • stamp – The DTSTAMP of the component. If None, this is set to the current time.

  • uid – The uid of the component. If None, this is set to a new uuid.uuid4().

  • url – The url of the component.

Returns:

FreeBusy

Raises:

InvalidCalendar – If the content is not valid according to RFC 5545.

Warning

As time progresses, we will be stricter with the validation.

property organizer: vCalAddress | None#

ORGANIZER defines the organizer for a calendar component.

Property Parameters:

IANA, non-standard, language, common name, directory entry reference, and sent-by property parameters can be specified on this property.

Conformance:

This property MUST be specified in an iCalendar object that specifies a group-scheduled calendar entity. This property MUST be specified in an iCalendar object that specifies the publication of a calendar user’s busy time. This property MUST NOT be specified in an iCalendar object that specifies only a time zone definition or that defines calendar components that are not group-scheduled components, but are components only on a single user’s calendar.

Description:

This property is specified within the “VEVENT”, “VTODO”, and “VJOURNAL” calendar components to specify the organizer of a group-scheduled calendar entity. The property is specified within the “VFREEBUSY” calendar component to specify the calendar user requesting the free or busy time. When publishing a “VFREEBUSY” calendar component, the property is used to specify the calendar that the published busy time came from.

The property has the property parameters “CN”, for specifying the common or display name associated with the “Organizer”, “DIR”, for specifying a pointer to the directory information associated with the “Organizer”, “SENT-BY”, for specifying another calendar user that is acting on behalf of the “Organizer”. The non-standard parameters may also be specified on this property. If the “LANGUAGE” property parameter is specified, the identified language applies to the “CN” parameter value.

required = ('UID', 'DTSTAMP')#
singletons = ('CONTACT', 'DTSTART', 'DTEND', 'DTSTAMP', 'ORGANIZER', 'UID', 'URL')#
property start: date | None#

The DTSTART property.

The “DTSTART” property for a “VFREEBUSY” specifies the inclusive start of the component.

Accepted values: datetime, date. If the attribute has invalid values, we raise InvalidCalendar. If the value is absent, we return None. You can also delete the value with del or by setting it to None.

subcomponents: list[Component]#
property uid: str#

UID specifies the persistent, globally unique identifier for a component.

We recommend using uuid.uuid4() to generate new values.

Returns:

The value of the UID property as a string or "" if no value is set.

Description:

The “UID” itself MUST be a globally unique identifier. The generator of the identifier MUST guarantee that the identifier is unique.

This is the method for correlating scheduling messages with the referenced “VEVENT”, “VTODO”, or “VJOURNAL” calendar component. The full range of calendar components specified by a recurrence set is referenced by referring to just the “UID” property value corresponding to the calendar component. The “RECURRENCE-ID” property allows the reference to an individual instance within the recurrence set.

This property is an important method for group-scheduling applications to match requests with later replies, modifications, or deletion requests. Calendaring and scheduling applications MUST generate this property in “VEVENT”, “VTODO”, and “VJOURNAL” calendar components to assure interoperability with other group- scheduling applications. This identifier is created by the calendar system that generates an iCalendar object.

Implementations MUST be able to receive and persist values of at least 255 octets for this property, but they MUST NOT truncate values in the middle of a UTF-8 multi-octet sequence.

RFC 7986 states that UID can be used, for example, to identify duplicate calendar streams that a client may have been given access to. It can be used in conjunction with the “LAST-MODIFIED” property also specified on the “VCALENDAR” object to identify the most recent version of a calendar.

Conformance:

RFC 5545 states that the “UID” property can be specified on “VEVENT”, “VTODO”, and “VJOURNAL” calendar components. RFC 7986 modifies the definition of the “UID” property to allow it to be defined in an iCalendar object. RFC 9074 adds a “UID” property to “VALARM” components to allow a unique identifier to be specified. The value of this property can then be used to refer uniquely to the “VALARM” component.

This property can be specified once only.

Security:

RFC 7986 states that UID values MUST NOT include any data that might identify a user, host, domain, or any other security- or privacy-sensitive information. It is RECOMMENDED that calendar user agents now generate “UID” values that are hex-encoded random Universally Unique Identifier (UUID) values as defined in Sections 4.4 and 4.5 of RFC 4122. You can use the uuid module to generate new UUIDs.

Compatibility:

For Alarms, X-ALARMUID is also considered.

Examples

The following is an example of such a property value: 5FC53010-1267-4F8E-BC28-1D7AE55A7C99.

Set the UID of a calendar:

>>> from icalendar import Calendar
>>> from uuid import uuid4
>>> calendar = Calendar()
>>> calendar.uid = uuid4()
>>> print(calendar.to_ical())
BEGIN:VCALENDAR
UID:d755cef5-2311-46ed-a0e1-6733c9e15c63
END:VCALENDAR
property url: str#

A Uniform Resource Locator (URL) associated with the iCalendar object.

Description:

This property may be used in a calendar component to convey a location where a more dynamic rendition of the calendar information associated with the calendar component can be found. This memo does not attempt to standardize the form of the URI, nor the format of the resource pointed to by the property value. If the URL property and Content-Location MIME header are both specified, they MUST point to the same resource.

Conformance:

This property can be specified once in the “VEVENT”, “VTODO”, “VJOURNAL”, or “VFREEBUSY” calendar components. Since RFC 7986, this property can also be defined on a “VCALENDAR”.

Example

The following is an example of this property:

URL:http://example.com/pub/calendars/jsmith/mytime.ics
class icalendar.cal.Journal(*args, **kwargs)[source]#

Bases: Component

A descriptive text at a certain time or associated with a component.

Description:

A “VJOURNAL” calendar component is a grouping of component properties that represent one or more descriptive text notes associated with a particular calendar date. The “DTSTART” property is used to specify the calendar date with which the journal entry is associated. Generally, it will have a DATE value data type, but it can also be used to specify a DATE-TIME value data type. Examples of a journal entry include a daily record of a legislative body or a journal entry of individual telephone contacts for the day or an ordered list of accomplishments for the day.

Examples

Create a new Journal:

>>> from icalendar import Journal
>>> journal = Journal.new()
>>> print(journal.to_ical())
BEGIN:VJOURNAL
DTSTAMP:20250517T080612Z
UID:d755cef5-2311-46ed-a0e1-6733c9e15c63
END:VJOURNAL
property DTSTART: date | None#

The DTSTART property.

The “DTSTART” property for a “VJOURNAL” that specifies the exact date at which the journal entry was made.

Accepted values: datetime, date. If the attribute has invalid values, we raise InvalidCalendar. If the value is absent, we return None. You can also delete the value with del or by setting it to None.

property attendees: list[vCalAddress]#

ATTENDEE defines one or more “Attendees” within a calendar component.

Conformance:

This property MUST be specified in an iCalendar object that specifies a group-scheduled calendar entity. This property MUST NOT be specified in an iCalendar object when publishing the calendar information (e.g., NOT in an iCalendar object that specifies the publication of a calendar user’s busy time, event, to-do, or journal). This property is not specified in an iCalendar object that specifies only a time zone definition or that defines calendar components that are not group-scheduled components, but are components only on a single user’s calendar.

Description:

This property MUST only be specified within calendar components to specify participants, non-participants, and the chair of a group-scheduled calendar entity. The property is specified within an “EMAIL” category of the “VALARM” calendar component to specify an email address that is to receive the email type of iCalendar alarm.

Examples

Add a new attendee to an existing event.

>>> from icalendar import Event, vCalAddress
>>> event = Event()
>>> event.attendees.append(vCalAddress("mailto:me@my-domain.com"))
>>> print(event.to_ical())
BEGIN:VEVENT
ATTENDEE:mailto:me@my-domain.com
END:VEVENT

Create an email alarm with several attendees:

>>> from icalendar import Alarm, vCalAddress
>>> alarm = Alarm.new(attendees = [
...     vCalAddress("mailto:me@my-domain.com"),
...     vCalAddress("mailto:you@my-domain.com"),
... ], summary = "Email alarm")
>>> print(alarm.to_ical())
BEGIN:VALARM
ATTENDEE:mailto:me@my-domain.com
ATTENDEE:mailto:you@my-domain.com
SUMMARY:Email alarm
END:VALARM
property categories: list[str]#

This property defines the categories for a component.

Property Parameters:

IANA, non-standard, and language property parameters can be specified on this property.

Conformance:

The property can be specified within “VEVENT”, “VTODO”, or “VJOURNAL” calendar components. Since RFC 7986 it can also be defined on a “VCALENDAR” component.

Description:

This property is used to specify categories or subtypes of the calendar component. The categories are useful in searching for a calendar component of a particular type and category. Within the “VEVENT”, “VTODO”, or “VJOURNAL” calendar components, more than one category can be specified as a COMMA-separated list of categories.

Example

Below, we add the categories to an event:

>>> from icalendar import Event
>>> event = Event()
>>> event.categories = ["Work", "Meeting"]
>>> print(event.to_ical())
BEGIN:VEVENT
CATEGORIES:Work,Meeting
END:VEVENT
>>> event.categories.append("Lecture")
>>> event.categories == ["Work", "Meeting", "Lecture"]
True

Note

At present, we do not take the LANGUAGE parameter into account.

property classification: StrEnum#

CLASS specifies the class of the calendar component.

Returns:

icalendar.enums.CLASS

Description:

An access classification is only one component of the general security system within a calendar application. It provides a method of capturing the scope of the access the calendar owner intends for information within an individual calendar entry. The access classification of an individual iCalendar component is useful when measured along with the other security components of a calendar system (e.g., calendar user authentication, authorization, access rights, access role, etc.). Hence, the semantics of the individual access classifications cannot be completely defined by this memo alone. Additionally, due to the “blind” nature of most exchange processes using this memo, these access classifications cannot serve as an enforcement statement for a system receiving an iCalendar object. Rather, they provide a method for capturing the intention of the calendar owner for the access to the calendar component. If not specified in a component that allows this property, the default value is PUBLIC. Applications MUST treat x-name and iana-token values they don’t recognize the same way as they would the PRIVATE value.

property color: str#

This property specifies a color used for displaying the component.

This implements RFC 7986 COLOR property.

Property Parameters:

IANA and non-standard property parameters can be specified on this property.

Conformance:

This property can be specified once in an iCalendar object or in VEVENT, VTODO, or VJOURNAL calendar components.

Description:

This property specifies a color that clients MAY use when presenting the relevant data to a user. Typically, this would appear as the “background” color of events or tasks. The value is a case-insensitive color name taken from the CSS3 set of names, defined in Section 4.3 of W3C.REC-css3-color-20110607.

Example

"turquoise", "#ffffff"

>>> from icalendar import Todo
>>> todo = Todo()
>>> todo.color = "green"
>>> print(todo.to_ical())
BEGIN:VTODO
COLOR:green
END:VTODO
property contacts: list[str]#

Contact information associated with the calendar component.

Purpose:

This property is used to represent contact information or alternately a reference to contact information associated with the calendar component.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

In RFC 5545, this property can be specified in a “VEVENT”, “VTODO”, “VJOURNAL”, or “VFREEBUSY” calendar component. In RFC 7953, this property can be specified in a “VAVAILABILITY” amd “VAVAILABLE” calendar component.

Description:

The property value consists of textual contact information. An alternative representation for the property value can also be specified that refers to a URI pointing to an alternate form, such as a vCard RFC 2426, for the contact information.

Example

The following is an example of this property referencing textual contact information:

CONTACT:Jim Dolittle\, ABC Industries\, +1-919-555-1234

The following is an example of this property with an alternate representation of an LDAP URI to a directory entry containing the contact information:

CONTACT;ALTREP="ldap://example.com:6666/o=ABC%20Industries\,
c=US???(cn=Jim%20Dolittle)":Jim Dolittle\, ABC Industries\,
+1-919-555-1234

The following is an example of this property with an alternate representation of a MIME body part containing the contact information, such as a vCard RFC 2426 embedded in a text/ directory media type RFC 2425:

CONTACT;ALTREP="CID:part3.msg970930T083000SILVER@example.com":
 Jim Dolittle\, ABC Industries\, +1-919-555-1234

The following is an example of this property referencing a network resource, such as a vCard RFC 2426 object containing the contact information:

CONTACT;ALTREP="http://example.com/pdi/jdoe.vcf":Jim
 Dolittle\, ABC Industries\, +1-919-555-1234
property description: str#

The concatenated descriptions of the journal.

A Journal can have several descriptions. This is a compatibility method.

property descriptions: list[str]#

DESCRIPTION provides a more complete description of the calendar component than that provided by the “SUMMARY” property.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

The property can be specified multiple times only within a “VJOURNAL” calendar component.

Description:

This property is used in the “VJOURNAL” calendar component to capture one or more textual journal entries.

Examples

The following is an example of this property with formatted line breaks in the property value:

DESCRIPTION:Meeting to provide technical review for "Phoenix"
 design.\nHappy Face Conference Room. Phoenix design team
 MUST attend this meeting.\nRSVP to team leader.
property duration: timedelta#

timedelta(0).

Type:

The journal has no duration

property end: date#

The start of the Journal.

The “DTSTART” property is used to specify the calendar date with which the journal entry is associated.

property exdates: list[date | datetime]#

EXDATE defines the list of DATE-TIME exceptions for recurring components.

EXDATE is defined in RFC 5545.

Value Type:

The default value type for this property is DATE-TIME. The value type can be set to DATE.

Property Parameters:

IANA, non-standard, value data type, and time zone identifier property parameters can be specified on this property.

Conformance:

This property can be specified in recurring “VEVENT”, “VTODO”, and “VJOURNAL” calendar components as well as in the “STANDARD” and “DAYLIGHT” sub-components of the “VTIMEZONE” calendar component.

Description:

The exception dates, if specified, are used in computing the recurrence set. The recurrence set is the complete set of recurrence instances for a calendar component. The recurrence set is generated by considering the initial “DTSTART” property along with the “RRULE”, “RDATE”, and “EXDATE” properties contained within the recurring component. The “DTSTART” property defines the first instance in the recurrence set. The “DTSTART” property value SHOULD match the pattern of the recurrence rule, if specified. The recurrence set generated with a “DTSTART” property value that doesn’t match the pattern of the rule is undefined. The final recurrence set is generated by gathering all of the start DATE-TIME values generated by any of the specified “RRULE” and “RDATE” properties, and then excluding any start DATE-TIME values specified by “EXDATE” properties. This implies that start DATE-TIME values specified by “EXDATE” properties take precedence over those specified by inclusion properties (i.e., “RDATE” and “RRULE”). When duplicate instances are generated by the “RRULE” and “RDATE” properties, only one recurrence is considered. Duplicate instances are ignored.

The “EXDATE” property can be used to exclude the value specified in “DTSTART”. However, in such cases, the original “DTSTART” date MUST still be maintained by the calendaring and scheduling system because the original “DTSTART” value has inherent usage dependencies by other properties such as the “RECURRENCE-ID”.

Example

Below, we add an exdate in a list and get the resulting list of exdates.

>>> from icalendar import Event
>>> from datetime import datetime
>>> event = Event()

# Add a list of excluded dates
>>> event.add("EXDATE", [datetime(2025, 4, 28, 16, 5)])
>>> event.exdates
[datetime.datetime(2025, 4, 28, 16, 5)]

Note

You cannot modify the EXDATE value by modifying the result. Use icalendar.cal.Component.add() to add values.

If you want to compute recurrences, have a look at Related projects.

property images: list[Image]#

IMAGE specifies an image associated with the calendar or a calendar component.

Description:

This property specifies an image for an iCalendar object or a calendar component via a URI or directly with inline data that can be used by calendar user agents when presenting the calendar data to a user. Multiple properties MAY be used to specify alternative sets of images with, for example, varying media subtypes, resolutions, or sizes. When multiple properties are present, calendar user agents SHOULD display only one of them, picking one that provides the most appropriate image quality, or display none. The “DISPLAY” parameter is used to indicate the intended display mode for the image. The “ALTREP” parameter, defined in RFC 5545, can be used to provide a “clickable” image where the URI in the parameter value can be “launched” by a click on the image in the calendar user agent.

Conformance:

This property can be specified multiple times in an iCalendar object or in “VEVENT”, “VTODO”, or “VJOURNAL” calendar components.

Note

At the present moment, this property is read-only. If you require a setter, please open an issue or a pull request.

multiple = ('ATTACH', 'ATTENDEE', 'CATEGORIES', 'COMMENT', 'CONTACT', 'EXDATE', 'RELATED', 'RDATE', 'RRULE', 'RSTATUS', 'DESCRIPTION')#
name = 'VJOURNAL'#
classmethod new(attendees: list[vCalAddress] | None = None, categories: Sequence[str] = (), classification: CLASS | None = None, color: str | None = None, comments: list[str] | str | None = None, contacts: list[str] | str | None = None, created: date | None = None, description: str | Sequence[str] | None = None, last_modified: date | None = None, organizer: vCalAddress | str | None = None, sequence: int | None = None, stamp: date | None = None, start: date | datetime | None = None, status: STATUS | None = None, summary: str | None = None, uid: str | uuid.UUID | None = None, url: str | None = None)[source]#

Create a new journal entry with all required properties.

This creates a new Journal in accordance with RFC 5545.

Parameters:
Returns:

Journal

Raises:

InvalidCalendar – If the content is not valid according to RFC 5545.

Warning

As time progresses, we will be stricter with the validation.

property organizer: vCalAddress | None#

ORGANIZER defines the organizer for a calendar component.

Property Parameters:

IANA, non-standard, language, common name, directory entry reference, and sent-by property parameters can be specified on this property.

Conformance:

This property MUST be specified in an iCalendar object that specifies a group-scheduled calendar entity. This property MUST be specified in an iCalendar object that specifies the publication of a calendar user’s busy time. This property MUST NOT be specified in an iCalendar object that specifies only a time zone definition or that defines calendar components that are not group-scheduled components, but are components only on a single user’s calendar.

Description:

This property is specified within the “VEVENT”, “VTODO”, and “VJOURNAL” calendar components to specify the organizer of a group-scheduled calendar entity. The property is specified within the “VFREEBUSY” calendar component to specify the calendar user requesting the free or busy time. When publishing a “VFREEBUSY” calendar component, the property is used to specify the calendar that the published busy time came from.

The property has the property parameters “CN”, for specifying the common or display name associated with the “Organizer”, “DIR”, for specifying a pointer to the directory information associated with the “Organizer”, “SENT-BY”, for specifying another calendar user that is acting on behalf of the “Organizer”. The non-standard parameters may also be specified on this property. If the “LANGUAGE” property parameter is specified, the identified language applies to the “CN” parameter value.

property rdates: list[tuple[date, None] | tuple[datetime, None] | tuple[datetime, datetime]]#

The RDATE property defines the list of DATE-TIME values for recurring components.

RDATE is defined in RFC 5545. The return value is a list of tuples (start, end).

start can be a datetime.date or a datetime.datetime, with and without timezone.

end is None if the end is not specified and a datetime.datetime if the end is specified.

Value Type:

The default value type for this property is DATE-TIME. The value type can be set to DATE or PERIOD.

Property Parameters:

IANA, non-standard, value data type, and time zone identifier property parameters can be specified on this property.

Conformance:

This property can be specified in recurring “VEVENT”, “VTODO”, and “VJOURNAL” calendar components as well as in the “STANDARD” and “DAYLIGHT” sub-components of the “VTIMEZONE” calendar component.

Description:

This property can appear along with the “RRULE” property to define an aggregate set of repeating occurrences. When they both appear in a recurring component, the recurrence instances are defined by the union of occurrences defined by both the “RDATE” and “RRULE”.

The recurrence dates, if specified, are used in computing the recurrence set. The recurrence set is the complete set of recurrence instances for a calendar component. The recurrence set is generated by considering the initial “DTSTART” property along with the “RRULE”, “RDATE”, and “EXDATE” properties contained within the recurring component. The “DTSTART” property defines the first instance in the recurrence set. The “DTSTART” property value SHOULD match the pattern of the recurrence rule, if specified. The recurrence set generated with a “DTSTART” property value that doesn’t match the pattern of the rule is undefined. The final recurrence set is generated by gathering all of the start DATE-TIME values generated by any of the specified “RRULE” and “RDATE” properties, and then excluding any start DATE-TIME values specified by “EXDATE” properties. This implies that start DATE-TIME values specified by “EXDATE” properties take precedence over those specified by inclusion properties (i.e., “RDATE” and “RRULE”). Where duplicate instances are generated by the “RRULE” and “RDATE” properties, only one recurrence is considered. Duplicate instances are ignored.

Example

Below, we set one RDATE in a list and get the resulting tuple of start and end.

>>> from icalendar import Event
>>> from datetime import datetime
>>> event = Event()

# Add a list of recurrence dates
>>> event.add("RDATE", [datetime(2025, 4, 28, 16, 5)])
>>> event.rdates
[(datetime.datetime(2025, 4, 28, 16, 5), None)]

Note

You cannot modify the RDATE value by modifying the result. Use icalendar.cal.Component.add() to add values.

If you want to compute recurrences, have a look at Related projects.

required = ('UID', 'DTSTAMP')#
property rrules: list[vRecur]#

RRULE defines a rule or repeating pattern for recurring components.

RRULE is defined in RFC 5545. RFC 7529 adds the SKIP parameter icalendar.prop.vSkip.

Property Parameters:

IANA and non-standard property parameters can be specified on this property.

Conformance:

This property can be specified in recurring “VEVENT”, “VTODO”, and “VJOURNAL” calendar components as well as in the “STANDARD” and “DAYLIGHT” sub-components of the “VTIMEZONE” calendar component, but it SHOULD NOT be specified more than once. The recurrence set generated with multiple “RRULE” properties is undefined.

Description:

The recurrence rule, if specified, is used in computing the recurrence set. The recurrence set is the complete set of recurrence instances for a calendar component. The recurrence set is generated by considering the initial “DTSTART” property along with the “RRULE”, “RDATE”, and “EXDATE” properties contained within the recurring component. The “DTSTART” property defines the first instance in the recurrence set. The “DTSTART” property value SHOULD be synchronized with the recurrence rule, if specified. The recurrence set generated with a “DTSTART” property value not synchronized with the recurrence rule is undefined. The final recurrence set is generated by gathering all of the start DATE-TIME values generated by any of the specified “RRULE” and “RDATE” properties, and then excluding any start DATE-TIME values specified by “EXDATE” properties. This implies that start DATE- TIME values specified by “EXDATE” properties take precedence over those specified by inclusion properties (i.e., “RDATE” and “RRULE”). Where duplicate instances are generated by the “RRULE” and “RDATE” properties, only one recurrence is considered. Duplicate instances are ignored.

The “DTSTART” property specified within the iCalendar object defines the first instance of the recurrence. In most cases, a “DTSTART” property of DATE-TIME value type used with a recurrence rule, should be specified as a date with local time and time zone reference to make sure all the recurrence instances start at the same local time regardless of time zone changes.

If the duration of the recurring component is specified with the “DTEND” or “DUE” property, then the same exact duration will apply to all the members of the generated recurrence set. Else, if the duration of the recurring component is specified with the “DURATION” property, then the same nominal duration will apply to all the members of the generated recurrence set and the exact duration of each recurrence instance will depend on its specific start time. For example, recurrence instances of a nominal duration of one day will have an exact duration of more or less than 24 hours on a day where a time zone shift occurs. The duration of a specific recurrence may be modified in an exception component or simply by using an “RDATE” property of PERIOD value type.

Examples

Daily for 10 occurrences:

>>> from icalendar import Event
>>> from datetime import datetime
>>> from zoneinfo import ZoneInfo
>>> event = Event()
>>> event.start = datetime(1997, 9, 2, 9, 0, tzinfo=ZoneInfo("America/New_York"))
>>> event.add("RRULE", "FREQ=DAILY;COUNT=10")
>>> print(event.to_ical())
BEGIN:VEVENT
DTSTART;TZID=America/New_York:19970902T090000
RRULE:FREQ=DAILY;COUNT=10
END:VEVENT
>>> event.rrules
[vRecur({'FREQ': ['DAILY'], 'COUNT': [10]})]

Daily until December 24, 1997:

>>> from icalendar import Event, vRecur
>>> from datetime import datetime
>>> from zoneinfo import ZoneInfo
>>> event = Event()
>>> event.start = datetime(1997, 9, 2, 9, 0, tzinfo=ZoneInfo("America/New_York"))
>>> event.add("RRULE", vRecur({"FREQ": ["DAILY"]}, until=datetime(1997, 12, 24, tzinfo=ZoneInfo("UTC"))))
>>> print(event.to_ical())
BEGIN:VEVENT
DTSTART;TZID=America/New_York:19970902T090000
RRULE:FREQ=DAILY;UNTIL=19971224T000000Z
END:VEVENT
>>> event.rrules
[vRecur({'FREQ': ['DAILY'], 'UNTIL': [datetime.datetime(1997, 12, 24, 0, 0, tzinfo=ZoneInfo(key='UTC'))]})]

Note

You cannot modify the RRULE value by modifying the result. Use icalendar.cal.Component.add() to add values.

If you want to compute recurrences, have a look at Related projects.

property sequence: int#

This property defines the revision sequence number of the calendar component within a sequence of revisions.

Value Type:

INTEGER

Property Parameters:

IANA and non-standard property parameters can be specified on this property.

Conformance:

The property can be specified in “VEVENT”, “VTODO”, or “VJOURNAL” calendar component.

Description:

When a calendar component is created, its sequence number is 0. It is monotonically incremented by the “Organizer’s” CUA each time the “Organizer” makes a significant revision to the calendar component.

The “Organizer” includes this property in an iCalendar object that it sends to an “Attendee” to specify the current version of the calendar component.

The “Attendee” includes this property in an iCalendar object that it sends to the “Organizer” to specify the version of the calendar component to which the “Attendee” is referring.

A change to the sequence number is not the mechanism that an “Organizer” uses to request a response from the “Attendees”. The “RSVP” parameter on the “ATTENDEE” property is used by the “Organizer” to indicate that a response from the “Attendees” is requested.

Recurrence instances of a recurring component MAY have different sequence numbers.

Examples

The following is an example of this property for a calendar component that was just created by the “Organizer”:

>>> from icalendar import Event
>>> event = Event()
>>> event.sequence
0

The following is an example of this property for a calendar component that has been revised 10 different times by the “Organizer”:

>>> from icalendar import Calendar
>>> calendar = Calendar.example("issue_156_RDATE_with_PERIOD_TZID_khal")
>>> event = calendar.events[0]
>>> event.sequence
10
singletons = ('CLASS', 'COLOR', 'CREATED', 'DTSTART', 'DTSTAMP', 'LAST-MODIFIED', 'ORGANIZER', 'RECURRENCE-ID', 'SEQUENCE', 'STATUS', 'SUMMARY', 'UID', 'URL')#
property start: date#

The start of the Journal.

The “DTSTART” property is used to specify the calendar date with which the journal entry is associated.

property status: StrEnum#

STATUS defines the overall status or confirmation for the calendar component.

Returns:

icalendar.enums.STATUS

The default value is "".

Description:

In a group-scheduled calendar component, the property is used by the “Organizer” to provide a confirmation of the event to the “Attendees”. For example in a “VEVENT” calendar component, the “Organizer” can indicate that a meeting is tentative, confirmed, or cancelled. In a “VTODO” calendar component, the “Organizer” can indicate that an action item needs action, is completed, is in process or being worked on, or has been cancelled. In a “VJOURNAL” calendar component, the “Organizer” can indicate that a journal entry is draft, final, or has been cancelled or removed.

subcomponents: list[Component]#
property summary: str | None#

SUMMARY defines a short summary or subject for the calendar component.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

The property can be specified in “VEVENT”, “VTODO”, “VJOURNAL”, or “VALARM” calendar components.

Description:

This property is used in the “VEVENT”, “VTODO”, and “VJOURNAL” calendar components to capture a short, one-line summary about the activity or journal entry.

This property is used in the “VALARM” calendar component to capture the subject of an EMAIL category of alarm.

Examples

The following is an example of this property:

SUMMARY:Department Party
property uid: str#

UID specifies the persistent, globally unique identifier for a component.

We recommend using uuid.uuid4() to generate new values.

Returns:

The value of the UID property as a string or "" if no value is set.

Description:

The “UID” itself MUST be a globally unique identifier. The generator of the identifier MUST guarantee that the identifier is unique.

This is the method for correlating scheduling messages with the referenced “VEVENT”, “VTODO”, or “VJOURNAL” calendar component. The full range of calendar components specified by a recurrence set is referenced by referring to just the “UID” property value corresponding to the calendar component. The “RECURRENCE-ID” property allows the reference to an individual instance within the recurrence set.

This property is an important method for group-scheduling applications to match requests with later replies, modifications, or deletion requests. Calendaring and scheduling applications MUST generate this property in “VEVENT”, “VTODO”, and “VJOURNAL” calendar components to assure interoperability with other group- scheduling applications. This identifier is created by the calendar system that generates an iCalendar object.

Implementations MUST be able to receive and persist values of at least 255 octets for this property, but they MUST NOT truncate values in the middle of a UTF-8 multi-octet sequence.

RFC 7986 states that UID can be used, for example, to identify duplicate calendar streams that a client may have been given access to. It can be used in conjunction with the “LAST-MODIFIED” property also specified on the “VCALENDAR” object to identify the most recent version of a calendar.

Conformance:

RFC 5545 states that the “UID” property can be specified on “VEVENT”, “VTODO”, and “VJOURNAL” calendar components. RFC 7986 modifies the definition of the “UID” property to allow it to be defined in an iCalendar object. RFC 9074 adds a “UID” property to “VALARM” components to allow a unique identifier to be specified. The value of this property can then be used to refer uniquely to the “VALARM” component.

This property can be specified once only.

Security:

RFC 7986 states that UID values MUST NOT include any data that might identify a user, host, domain, or any other security- or privacy-sensitive information. It is RECOMMENDED that calendar user agents now generate “UID” values that are hex-encoded random Universally Unique Identifier (UUID) values as defined in Sections 4.4 and 4.5 of RFC 4122. You can use the uuid module to generate new UUIDs.

Compatibility:

For Alarms, X-ALARMUID is also considered.

Examples

The following is an example of such a property value: 5FC53010-1267-4F8E-BC28-1D7AE55A7C99.

Set the UID of a calendar:

>>> from icalendar import Calendar
>>> from uuid import uuid4
>>> calendar = Calendar()
>>> calendar.uid = uuid4()
>>> print(calendar.to_ical())
BEGIN:VCALENDAR
UID:d755cef5-2311-46ed-a0e1-6733c9e15c63
END:VCALENDAR
property url: str#

A Uniform Resource Locator (URL) associated with the iCalendar object.

Description:

This property may be used in a calendar component to convey a location where a more dynamic rendition of the calendar information associated with the calendar component can be found. This memo does not attempt to standardize the form of the URI, nor the format of the resource pointed to by the property value. If the URL property and Content-Location MIME header are both specified, they MUST point to the same resource.

Conformance:

This property can be specified once in the “VEVENT”, “VTODO”, “VJOURNAL”, or “VFREEBUSY” calendar components. Since RFC 7986, this property can also be defined on a “VCALENDAR”.

Example

The following is an example of this property:

URL:http://example.com/pub/calendars/jsmith/mytime.ics
class icalendar.cal.Timezone(*args, **kwargs)[source]#

Bases: Component

A “VTIMEZONE” calendar component is a grouping of component properties that defines a time zone. It is used to describe the way in which a time zone changes its offset from UTC over time.

DEFAULT_FIRST_DATE = datetime.date(1970, 1, 1)#
DEFAULT_LAST_DATE = datetime.date(2038, 1, 1)#
canonical_order = ('TZID',)#
property daylight: list[TimezoneDaylight]#

The DAYLIGHT subcomponents as a list.

These are for the daylight saving time.

classmethod example(name: str = 'pacific_fiji') → Calendar[source]#

Return the timezone example with the given name.

classmethod from_tzid(tzid: str, tzp: TZP = TZP('zoneinfo'), first_date: date = datetime.date(1970, 1, 1), last_date: date = datetime.date(2038, 1, 1)) → Timezone[source]#

Create a VTIMEZONE from a tzid like "Europe/Berlin".

Parameters:

  • tzid – the id of the timezone

  • tzp – the timezone provider

  • first_date – a datetime that is earlier than anything that happens in the calendar

  • last_date – a datetime that is later than anything that happens in the calendar

Raises:

ValueError – If the tzid is unknown.

>>> from icalendar import Timezone
>>> tz = Timezone.from_tzid("Europe/Berlin")
>>> print(tz.to_ical()[:36])
BEGIN:VTIMEZONE
TZID:Europe/Berlin

Note

This can take some time. Please cache the results.

classmethod from_tzinfo(timezone: tzinfo, tzid: str | None = None, first_date: date = datetime.date(1970, 1, 1), last_date: date = datetime.date(2038, 1, 1)) → Timezone[source]#

Return a VTIMEZONE component from a timezone object.

This works with pytz and zoneinfo and any other timezone. The offsets are calculated from the tzinfo object.

Parameters:

Parameters:

  • tzinfo – the timezone object

  • tzid – the tzid for this timezone. If None, it will be extracted from the tzinfo.

  • first_date – a datetime that is earlier than anything that happens in the calendar

  • last_date – a datetime that is later than anything that happens in the calendar

Raises:

ValueError – If we have no tzid and cannot extract one.

Note

This can take some time. Please cache the results.

get_transitions() → tuple[list[datetime], list[tuple[timedelta, timedelta, str]]][source]#

Return a tuple of (transition_times, transition_info)

  • transition_times = [datetime, …]

  • transition_info = [(TZOFFSETTO, dts_offset, tzname)]

name = 'VTIMEZONE'#
required = ('TZID',)#
singletons = ('TZID', 'LAST-MODIFIED', 'TZURL')#
property standard: list[TimezoneStandard]#

The STANDARD subcomponents as a list.

subcomponents: list[TimezoneStandard | TimezoneDaylight]#
to_tz(tzp: TZP = TZP('zoneinfo'), lookup_tzid: bool = True)[source]#

convert this VTIMEZONE component to a timezone object

Parameters:

  • tzp – timezone provider to use

  • lookup_tzid – whether to use the TZID property to look up existing timezone definitions with tzp. If it is False, a new timezone will be created. If it is True, the existing timezone will be used if it exists, otherwise a new timezone will be created.

property tz_name: str#

Return the name of the timezone component.

Please note that the names of the timezone are different from this name and may change with winter/summer time.

class icalendar.cal.TimezoneDaylight(*args, **kwargs)[source]#

Bases: Component

The “DAYLIGHT” sub-component of “VTIMEZONE” defines the daylight saving time offset from UTC for a time zone. It represents a time zone’s daylight saving time, typically used during summer months in locations that observe Daylight Saving Time.

property DTSTART: datetime | None#

The DTSTART property.

The mandatory “DTSTART” property gives the effective onset date

and local time for the time zone sub-component definition. “DTSTART” in this usage MUST be specified as a date with a local time value.

Accepted values: datetime. If the attribute has invalid values, we raise InvalidCalendar. If the value is absent, we return None. You can also delete the value with del or by setting it to None.

property TZOFFSETFROM: timedelta | None#

The TZOFFSETFROM property.

The mandatory “TZOFFSETFROM” property gives the UTC offset that is

in use when the onset of this time zone observance begins. “TZOFFSETFROM” is combined with “DTSTART” to define the effective onset for the time zone sub-component definition. For example, the following represents the time at which the observance of Standard Time took effect in Fall 1967 for New York City:

DTSTART:19671029T020000 TZOFFSETFROM:-0400

Accepted values: timedelta. If the attribute has invalid values, we raise InvalidCalendar. If the value is absent, we return None. You can also delete the value with del or by setting it to None.

property TZOFFSETTO: timedelta | None#

The TZOFFSETTO property.

The mandatory “TZOFFSETTO” property gives the UTC offset for the

time zone sub-component (Standard Time or Daylight Saving Time) when this observance is in use.

Accepted values: timedelta. If the attribute has invalid values, we raise InvalidCalendar. If the value is absent, we return None. You can also delete the value with del or by setting it to None.

property exdates: list[date | datetime]#

EXDATE defines the list of DATE-TIME exceptions for recurring components.

EXDATE is defined in RFC 5545.

Value Type:

The default value type for this property is DATE-TIME. The value type can be set to DATE.

Property Parameters:

IANA, non-standard, value data type, and time zone identifier property parameters can be specified on this property.

Conformance:

This property can be specified in recurring “VEVENT”, “VTODO”, and “VJOURNAL” calendar components as well as in the “STANDARD” and “DAYLIGHT” sub-components of the “VTIMEZONE” calendar component.

Description:

The exception dates, if specified, are used in computing the recurrence set. The recurrence set is the complete set of recurrence instances for a calendar component. The recurrence set is generated by considering the initial “DTSTART” property along with the “RRULE”, “RDATE”, and “EXDATE” properties contained within the recurring component. The “DTSTART” property defines the first instance in the recurrence set. The “DTSTART” property value SHOULD match the pattern of the recurrence rule, if specified. The recurrence set generated with a “DTSTART” property value that doesn’t match the pattern of the rule is undefined. The final recurrence set is generated by gathering all of the start DATE-TIME values generated by any of the specified “RRULE” and “RDATE” properties, and then excluding any start DATE-TIME values specified by “EXDATE” properties. This implies that start DATE-TIME values specified by “EXDATE” properties take precedence over those specified by inclusion properties (i.e., “RDATE” and “RRULE”). When duplicate instances are generated by the “RRULE” and “RDATE” properties, only one recurrence is considered. Duplicate instances are ignored.

The “EXDATE” property can be used to exclude the value specified in “DTSTART”. However, in such cases, the original “DTSTART” date MUST still be maintained by the calendaring and scheduling system because the original “DTSTART” value has inherent usage dependencies by other properties such as the “RECURRENCE-ID”.

Example

Below, we add an exdate in a list and get the resulting list of exdates.

>>> from icalendar import Event
>>> from datetime import datetime
>>> event = Event()

# Add a list of excluded dates
>>> event.add("EXDATE", [datetime(2025, 4, 28, 16, 5)])
>>> event.exdates
[datetime.datetime(2025, 4, 28, 16, 5)]

Note

You cannot modify the EXDATE value by modifying the result. Use icalendar.cal.Component.add() to add values.

If you want to compute recurrences, have a look at Related projects.

multiple = ('COMMENT', 'RDATE', 'TZNAME', 'RRULE', 'EXDATE')#
name = 'DAYLIGHT'#
property rdates: list[tuple[date, None] | tuple[datetime, None] | tuple[datetime, datetime]]#

The RDATE property defines the list of DATE-TIME values for recurring components.

RDATE is defined in RFC 5545. The return value is a list of tuples (start, end).

start can be a datetime.date or a datetime.datetime, with and without timezone.

end is None if the end is not specified and a datetime.datetime if the end is specified.

Value Type:

The default value type for this property is DATE-TIME. The value type can be set to DATE or PERIOD.

Property Parameters:

IANA, non-standard, value data type, and time zone identifier property parameters can be specified on this property.

Conformance:

This property can be specified in recurring “VEVENT”, “VTODO”, and “VJOURNAL” calendar components as well as in the “STANDARD” and “DAYLIGHT” sub-components of the “VTIMEZONE” calendar component.

Description:

This property can appear along with the “RRULE” property to define an aggregate set of repeating occurrences. When they both appear in a recurring component, the recurrence instances are defined by the union of occurrences defined by both the “RDATE” and “RRULE”.

The recurrence dates, if specified, are used in computing the recurrence set. The recurrence set is the complete set of recurrence instances for a calendar component. The recurrence set is generated by considering the initial “DTSTART” property along with the “RRULE”, “RDATE”, and “EXDATE” properties contained within the recurring component. The “DTSTART” property defines the first instance in the recurrence set. The “DTSTART” property value SHOULD match the pattern of the recurrence rule, if specified. The recurrence set generated with a “DTSTART” property value that doesn’t match the pattern of the rule is undefined. The final recurrence set is generated by gathering all of the start DATE-TIME values generated by any of the specified “RRULE” and “RDATE” properties, and then excluding any start DATE-TIME values specified by “EXDATE” properties. This implies that start DATE-TIME values specified by “EXDATE” properties take precedence over those specified by inclusion properties (i.e., “RDATE” and “RRULE”). Where duplicate instances are generated by the “RRULE” and “RDATE” properties, only one recurrence is considered. Duplicate instances are ignored.

Example

Below, we set one RDATE in a list and get the resulting tuple of start and end.

>>> from icalendar import Event
>>> from datetime import datetime
>>> event = Event()

# Add a list of recurrence dates
>>> event.add("RDATE", [datetime(2025, 4, 28, 16, 5)])
>>> event.rdates
[(datetime.datetime(2025, 4, 28, 16, 5), None)]

Note

You cannot modify the RDATE value by modifying the result. Use icalendar.cal.Component.add() to add values.

If you want to compute recurrences, have a look at Related projects.

required = ('DTSTART', 'TZOFFSETTO', 'TZOFFSETFROM')#
property rrules: list[vRecur]#

RRULE defines a rule or repeating pattern for recurring components.

RRULE is defined in RFC 5545. RFC 7529 adds the SKIP parameter icalendar.prop.vSkip.

Property Parameters:

IANA and non-standard property parameters can be specified on this property.

Conformance:

This property can be specified in recurring “VEVENT”, “VTODO”, and “VJOURNAL” calendar components as well as in the “STANDARD” and “DAYLIGHT” sub-components of the “VTIMEZONE” calendar component, but it SHOULD NOT be specified more than once. The recurrence set generated with multiple “RRULE” properties is undefined.

Description:

The recurrence rule, if specified, is used in computing the recurrence set. The recurrence set is the complete set of recurrence instances for a calendar component. The recurrence set is generated by considering the initial “DTSTART” property along with the “RRULE”, “RDATE”, and “EXDATE” properties contained within the recurring component. The “DTSTART” property defines the first instance in the recurrence set. The “DTSTART” property value SHOULD be synchronized with the recurrence rule, if specified. The recurrence set generated with a “DTSTART” property value not synchronized with the recurrence rule is undefined. The final recurrence set is generated by gathering all of the start DATE-TIME values generated by any of the specified “RRULE” and “RDATE” properties, and then excluding any start DATE-TIME values specified by “EXDATE” properties. This implies that start DATE- TIME values specified by “EXDATE” properties take precedence over those specified by inclusion properties (i.e., “RDATE” and “RRULE”). Where duplicate instances are generated by the “RRULE” and “RDATE” properties, only one recurrence is considered. Duplicate instances are ignored.

The “DTSTART” property specified within the iCalendar object defines the first instance of the recurrence. In most cases, a “DTSTART” property of DATE-TIME value type used with a recurrence rule, should be specified as a date with local time and time zone reference to make sure all the recurrence instances start at the same local time regardless of time zone changes.

If the duration of the recurring component is specified with the “DTEND” or “DUE” property, then the same exact duration will apply to all the members of the generated recurrence set. Else, if the duration of the recurring component is specified with the “DURATION” property, then the same nominal duration will apply to all the members of the generated recurrence set and the exact duration of each recurrence instance will depend on its specific start time. For example, recurrence instances of a nominal duration of one day will have an exact duration of more or less than 24 hours on a day where a time zone shift occurs. The duration of a specific recurrence may be modified in an exception component or simply by using an “RDATE” property of PERIOD value type.

Examples

Daily for 10 occurrences:

>>> from icalendar import Event
>>> from datetime import datetime
>>> from zoneinfo import ZoneInfo
>>> event = Event()
>>> event.start = datetime(1997, 9, 2, 9, 0, tzinfo=ZoneInfo("America/New_York"))
>>> event.add("RRULE", "FREQ=DAILY;COUNT=10")
>>> print(event.to_ical())
BEGIN:VEVENT
DTSTART;TZID=America/New_York:19970902T090000
RRULE:FREQ=DAILY;COUNT=10
END:VEVENT
>>> event.rrules
[vRecur({'FREQ': ['DAILY'], 'COUNT': [10]})]

Daily until December 24, 1997:

>>> from icalendar import Event, vRecur
>>> from datetime import datetime
>>> from zoneinfo import ZoneInfo
>>> event = Event()
>>> event.start = datetime(1997, 9, 2, 9, 0, tzinfo=ZoneInfo("America/New_York"))
>>> event.add("RRULE", vRecur({"FREQ": ["DAILY"]}, until=datetime(1997, 12, 24, tzinfo=ZoneInfo("UTC"))))
>>> print(event.to_ical())
BEGIN:VEVENT
DTSTART;TZID=America/New_York:19970902T090000
RRULE:FREQ=DAILY;UNTIL=19971224T000000Z
END:VEVENT
>>> event.rrules
[vRecur({'FREQ': ['DAILY'], 'UNTIL': [datetime.datetime(1997, 12, 24, 0, 0, tzinfo=ZoneInfo(key='UTC'))]})]

Note

You cannot modify the RRULE value by modifying the result. Use icalendar.cal.Component.add() to add values.

If you want to compute recurrences, have a look at Related projects.

singletons = ('DTSTART', 'TZOFFSETTO', 'TZOFFSETFROM')#
subcomponents: list[Component]#
class icalendar.cal.TimezoneStandard(*args, **kwargs)[source]#

Bases: Component

The “STANDARD” sub-component of “VTIMEZONE” defines the standard time offset from UTC for a time zone. It represents a time zone’s standard time, typically used during winter months in locations that observe Daylight Saving Time.

property DTSTART: datetime | None#

The DTSTART property.

The mandatory “DTSTART” property gives the effective onset date

and local time for the time zone sub-component definition. “DTSTART” in this usage MUST be specified as a date with a local time value.

Accepted values: datetime. If the attribute has invalid values, we raise InvalidCalendar. If the value is absent, we return None. You can also delete the value with del or by setting it to None.

property TZOFFSETFROM: timedelta | None#

The TZOFFSETFROM property.

The mandatory “TZOFFSETFROM” property gives the UTC offset that is

in use when the onset of this time zone observance begins. “TZOFFSETFROM” is combined with “DTSTART” to define the effective onset for the time zone sub-component definition. For example, the following represents the time at which the observance of Standard Time took effect in Fall 1967 for New York City:

DTSTART:19671029T020000 TZOFFSETFROM:-0400

Accepted values: timedelta. If the attribute has invalid values, we raise InvalidCalendar. If the value is absent, we return None. You can also delete the value with del or by setting it to None.

property TZOFFSETTO: timedelta | None#

The TZOFFSETTO property.

The mandatory “TZOFFSETTO” property gives the UTC offset for the

time zone sub-component (Standard Time or Daylight Saving Time) when this observance is in use.

Accepted values: timedelta. If the attribute has invalid values, we raise InvalidCalendar. If the value is absent, we return None. You can also delete the value with del or by setting it to None.

property exdates: list[date | datetime]#

EXDATE defines the list of DATE-TIME exceptions for recurring components.

EXDATE is defined in RFC 5545.

Value Type:

The default value type for this property is DATE-TIME. The value type can be set to DATE.

Property Parameters:

IANA, non-standard, value data type, and time zone identifier property parameters can be specified on this property.

Conformance:

This property can be specified in recurring “VEVENT”, “VTODO”, and “VJOURNAL” calendar components as well as in the “STANDARD” and “DAYLIGHT” sub-components of the “VTIMEZONE” calendar component.

Description:

The exception dates, if specified, are used in computing the recurrence set. The recurrence set is the complete set of recurrence instances for a calendar component. The recurrence set is generated by considering the initial “DTSTART” property along with the “RRULE”, “RDATE”, and “EXDATE” properties contained within the recurring component. The “DTSTART” property defines the first instance in the recurrence set. The “DTSTART” property value SHOULD match the pattern of the recurrence rule, if specified. The recurrence set generated with a “DTSTART” property value that doesn’t match the pattern of the rule is undefined. The final recurrence set is generated by gathering all of the start DATE-TIME values generated by any of the specified “RRULE” and “RDATE” properties, and then excluding any start DATE-TIME values specified by “EXDATE” properties. This implies that start DATE-TIME values specified by “EXDATE” properties take precedence over those specified by inclusion properties (i.e., “RDATE” and “RRULE”). When duplicate instances are generated by the “RRULE” and “RDATE” properties, only one recurrence is considered. Duplicate instances are ignored.

The “EXDATE” property can be used to exclude the value specified in “DTSTART”. However, in such cases, the original “DTSTART” date MUST still be maintained by the calendaring and scheduling system because the original “DTSTART” value has inherent usage dependencies by other properties such as the “RECURRENCE-ID”.

Example

Below, we add an exdate in a list and get the resulting list of exdates.

>>> from icalendar import Event
>>> from datetime import datetime
>>> event = Event()

# Add a list of excluded dates
>>> event.add("EXDATE", [datetime(2025, 4, 28, 16, 5)])
>>> event.exdates
[datetime.datetime(2025, 4, 28, 16, 5)]

Note

You cannot modify the EXDATE value by modifying the result. Use icalendar.cal.Component.add() to add values.

If you want to compute recurrences, have a look at Related projects.

multiple = ('COMMENT', 'RDATE', 'TZNAME', 'RRULE', 'EXDATE')#
name = 'STANDARD'#
property rdates: list[tuple[date, None] | tuple[datetime, None] | tuple[datetime, datetime]]#

The RDATE property defines the list of DATE-TIME values for recurring components.

RDATE is defined in RFC 5545. The return value is a list of tuples (start, end).

start can be a datetime.date or a datetime.datetime, with and without timezone.

end is None if the end is not specified and a datetime.datetime if the end is specified.

Value Type:

The default value type for this property is DATE-TIME. The value type can be set to DATE or PERIOD.

Property Parameters:

IANA, non-standard, value data type, and time zone identifier property parameters can be specified on this property.

Conformance:

This property can be specified in recurring “VEVENT”, “VTODO”, and “VJOURNAL” calendar components as well as in the “STANDARD” and “DAYLIGHT” sub-components of the “VTIMEZONE” calendar component.

Description:

This property can appear along with the “RRULE” property to define an aggregate set of repeating occurrences. When they both appear in a recurring component, the recurrence instances are defined by the union of occurrences defined by both the “RDATE” and “RRULE”.

The recurrence dates, if specified, are used in computing the recurrence set. The recurrence set is the complete set of recurrence instances for a calendar component. The recurrence set is generated by considering the initial “DTSTART” property along with the “RRULE”, “RDATE”, and “EXDATE” properties contained within the recurring component. The “DTSTART” property defines the first instance in the recurrence set. The “DTSTART” property value SHOULD match the pattern of the recurrence rule, if specified. The recurrence set generated with a “DTSTART” property value that doesn’t match the pattern of the rule is undefined. The final recurrence set is generated by gathering all of the start DATE-TIME values generated by any of the specified “RRULE” and “RDATE” properties, and then excluding any start DATE-TIME values specified by “EXDATE” properties. This implies that start DATE-TIME values specified by “EXDATE” properties take precedence over those specified by inclusion properties (i.e., “RDATE” and “RRULE”). Where duplicate instances are generated by the “RRULE” and “RDATE” properties, only one recurrence is considered. Duplicate instances are ignored.

Example

Below, we set one RDATE in a list and get the resulting tuple of start and end.

>>> from icalendar import Event
>>> from datetime import datetime
>>> event = Event()

# Add a list of recurrence dates
>>> event.add("RDATE", [datetime(2025, 4, 28, 16, 5)])
>>> event.rdates
[(datetime.datetime(2025, 4, 28, 16, 5), None)]

Note

You cannot modify the RDATE value by modifying the result. Use icalendar.cal.Component.add() to add values.

If you want to compute recurrences, have a look at Related projects.

required = ('DTSTART', 'TZOFFSETTO', 'TZOFFSETFROM')#
property rrules: list[vRecur]#

RRULE defines a rule or repeating pattern for recurring components.

RRULE is defined in RFC 5545. RFC 7529 adds the SKIP parameter icalendar.prop.vSkip.

Property Parameters:

IANA and non-standard property parameters can be specified on this property.

Conformance:

This property can be specified in recurring “VEVENT”, “VTODO”, and “VJOURNAL” calendar components as well as in the “STANDARD” and “DAYLIGHT” sub-components of the “VTIMEZONE” calendar component, but it SHOULD NOT be specified more than once. The recurrence set generated with multiple “RRULE” properties is undefined.

Description:

The recurrence rule, if specified, is used in computing the recurrence set. The recurrence set is the complete set of recurrence instances for a calendar component. The recurrence set is generated by considering the initial “DTSTART” property along with the “RRULE”, “RDATE”, and “EXDATE” properties contained within the recurring component. The “DTSTART” property defines the first instance in the recurrence set. The “DTSTART” property value SHOULD be synchronized with the recurrence rule, if specified. The recurrence set generated with a “DTSTART” property value not synchronized with the recurrence rule is undefined. The final recurrence set is generated by gathering all of the start DATE-TIME values generated by any of the specified “RRULE” and “RDATE” properties, and then excluding any start DATE-TIME values specified by “EXDATE” properties. This implies that start DATE- TIME values specified by “EXDATE” properties take precedence over those specified by inclusion properties (i.e., “RDATE” and “RRULE”). Where duplicate instances are generated by the “RRULE” and “RDATE” properties, only one recurrence is considered. Duplicate instances are ignored.

The “DTSTART” property specified within the iCalendar object defines the first instance of the recurrence. In most cases, a “DTSTART” property of DATE-TIME value type used with a recurrence rule, should be specified as a date with local time and time zone reference to make sure all the recurrence instances start at the same local time regardless of time zone changes.

If the duration of the recurring component is specified with the “DTEND” or “DUE” property, then the same exact duration will apply to all the members of the generated recurrence set. Else, if the duration of the recurring component is specified with the “DURATION” property, then the same nominal duration will apply to all the members of the generated recurrence set and the exact duration of each recurrence instance will depend on its specific start time. For example, recurrence instances of a nominal duration of one day will have an exact duration of more or less than 24 hours on a day where a time zone shift occurs. The duration of a specific recurrence may be modified in an exception component or simply by using an “RDATE” property of PERIOD value type.

Examples

Daily for 10 occurrences:

>>> from icalendar import Event
>>> from datetime import datetime
>>> from zoneinfo import ZoneInfo
>>> event = Event()
>>> event.start = datetime(1997, 9, 2, 9, 0, tzinfo=ZoneInfo("America/New_York"))
>>> event.add("RRULE", "FREQ=DAILY;COUNT=10")
>>> print(event.to_ical())
BEGIN:VEVENT
DTSTART;TZID=America/New_York:19970902T090000
RRULE:FREQ=DAILY;COUNT=10
END:VEVENT
>>> event.rrules
[vRecur({'FREQ': ['DAILY'], 'COUNT': [10]})]

Daily until December 24, 1997:

>>> from icalendar import Event, vRecur
>>> from datetime import datetime
>>> from zoneinfo import ZoneInfo
>>> event = Event()
>>> event.start = datetime(1997, 9, 2, 9, 0, tzinfo=ZoneInfo("America/New_York"))
>>> event.add("RRULE", vRecur({"FREQ": ["DAILY"]}, until=datetime(1997, 12, 24, tzinfo=ZoneInfo("UTC"))))
>>> print(event.to_ical())
BEGIN:VEVENT
DTSTART;TZID=America/New_York:19970902T090000
RRULE:FREQ=DAILY;UNTIL=19971224T000000Z
END:VEVENT
>>> event.rrules
[vRecur({'FREQ': ['DAILY'], 'UNTIL': [datetime.datetime(1997, 12, 24, 0, 0, tzinfo=ZoneInfo(key='UTC'))]})]

Note

You cannot modify the RRULE value by modifying the result. Use icalendar.cal.Component.add() to add values.

If you want to compute recurrences, have a look at Related projects.

singletons = ('DTSTART', 'TZOFFSETTO', 'TZOFFSETFROM')#
subcomponents: list[Component]#
class icalendar.cal.Todo(*args, **kwargs)[source]#

Bases: Component

A “VTODO” calendar component is a grouping of component properties that represents an action item or assignment. For example, it can be used to represent an item of work assigned to an individual, such as “Prepare for the upcoming conference seminar on Internet Calendaring”.

Examples

Create a new Todo:

>>> from icalendar import Todo
>>> todo = Todo.new()
>>> print(todo.to_ical())
BEGIN:VTODO
DTSTAMP:20250517T080612Z
UID:d755cef5-2311-46ed-a0e1-6733c9e15c63
END:VTODO
property DTSTART: date | None#

The DTSTART property.

The “DTSTART” property for a “VTODO” specifies the inclusive start of the Todo.

Accepted values: datetime, date. If the attribute has invalid values, we raise InvalidCalendar. If the value is absent, we return None. You can also delete the value with del or by setting it to None.

property DUE: date | None#

The DUE property.

The “DUE” property for a “VTODO” calendar component specifies the non-inclusive end of the Todo.

Accepted values: datetime, date. If the attribute has invalid values, we raise InvalidCalendar. If the value is absent, we return None. You can also delete the value with del or by setting it to None.

property DURATION: timedelta | None#

The DURATION property.

The “DTSTART” property for a “VTODO” specifies the inclusive start of the VTODO. The “DURATION” property in conjunction with the DTSTART property for a “VTODO” calendar component specifies the non-inclusive end of the event.

If you would like to calculate the duration of a VTODO, do not use this. Instead use the duration property (lower case).

property X_MOZ_LASTACK: datetime | None#

The X-MOZ-LASTACK property. datetime in UTC

All values will be converted to a datetime in UTC. Thunderbird: Alarms before this time are acknowledged.

property X_MOZ_SNOOZE_TIME: datetime | None#

The X-MOZ-SNOOZE-TIME property. datetime in UTC

All values will be converted to a datetime in UTC. Thunderbird: Alarms before this time are snoozed.

property alarms: Alarms#

Compute the alarm times for this component.

>>> from datetime import datetime
>>> from icalendar import Todo
>>> todo = Todo()  # empty without alarms
>>> todo.start = datetime(2024, 10, 26, 10, 21)
>>> len(todo.alarms.times)
0

Note that this only uses DTSTART and DUE, but ignores RDATE, EXDATE, and RRULE properties.

property attendees: list[vCalAddress]#

ATTENDEE defines one or more “Attendees” within a calendar component.

Conformance:

This property MUST be specified in an iCalendar object that specifies a group-scheduled calendar entity. This property MUST NOT be specified in an iCalendar object when publishing the calendar information (e.g., NOT in an iCalendar object that specifies the publication of a calendar user’s busy time, event, to-do, or journal). This property is not specified in an iCalendar object that specifies only a time zone definition or that defines calendar components that are not group-scheduled components, but are components only on a single user’s calendar.

Description:

This property MUST only be specified within calendar components to specify participants, non-participants, and the chair of a group-scheduled calendar entity. The property is specified within an “EMAIL” category of the “VALARM” calendar component to specify an email address that is to receive the email type of iCalendar alarm.

Examples

Add a new attendee to an existing event.

>>> from icalendar import Event, vCalAddress
>>> event = Event()
>>> event.attendees.append(vCalAddress("mailto:me@my-domain.com"))
>>> print(event.to_ical())
BEGIN:VEVENT
ATTENDEE:mailto:me@my-domain.com
END:VEVENT

Create an email alarm with several attendees:

>>> from icalendar import Alarm, vCalAddress
>>> alarm = Alarm.new(attendees = [
...     vCalAddress("mailto:me@my-domain.com"),
...     vCalAddress("mailto:you@my-domain.com"),
... ], summary = "Email alarm")
>>> print(alarm.to_ical())
BEGIN:VALARM
ATTENDEE:mailto:me@my-domain.com
ATTENDEE:mailto:you@my-domain.com
SUMMARY:Email alarm
END:VALARM
property categories: list[str]#

This property defines the categories for a component.

Property Parameters:

IANA, non-standard, and language property parameters can be specified on this property.

Conformance:

The property can be specified within “VEVENT”, “VTODO”, or “VJOURNAL” calendar components. Since RFC 7986 it can also be defined on a “VCALENDAR” component.

Description:

This property is used to specify categories or subtypes of the calendar component. The categories are useful in searching for a calendar component of a particular type and category. Within the “VEVENT”, “VTODO”, or “VJOURNAL” calendar components, more than one category can be specified as a COMMA-separated list of categories.

Example

Below, we add the categories to an event:

>>> from icalendar import Event
>>> event = Event()
>>> event.categories = ["Work", "Meeting"]
>>> print(event.to_ical())
BEGIN:VEVENT
CATEGORIES:Work,Meeting
END:VEVENT
>>> event.categories.append("Lecture")
>>> event.categories == ["Work", "Meeting", "Lecture"]
True

Note

At present, we do not take the LANGUAGE parameter into account.

property classification: StrEnum#

CLASS specifies the class of the calendar component.

Returns:

icalendar.enums.CLASS

Description:

An access classification is only one component of the general security system within a calendar application. It provides a method of capturing the scope of the access the calendar owner intends for information within an individual calendar entry. The access classification of an individual iCalendar component is useful when measured along with the other security components of a calendar system (e.g., calendar user authentication, authorization, access rights, access role, etc.). Hence, the semantics of the individual access classifications cannot be completely defined by this memo alone. Additionally, due to the “blind” nature of most exchange processes using this memo, these access classifications cannot serve as an enforcement statement for a system receiving an iCalendar object. Rather, they provide a method for capturing the intention of the calendar owner for the access to the calendar component. If not specified in a component that allows this property, the default value is PUBLIC. Applications MUST treat x-name and iana-token values they don’t recognize the same way as they would the PRIVATE value.

property color: str#

This property specifies a color used for displaying the component.

This implements RFC 7986 COLOR property.

Property Parameters:

IANA and non-standard property parameters can be specified on this property.

Conformance:

This property can be specified once in an iCalendar object or in VEVENT, VTODO, or VJOURNAL calendar components.

Description:

This property specifies a color that clients MAY use when presenting the relevant data to a user. Typically, this would appear as the “background” color of events or tasks. The value is a case-insensitive color name taken from the CSS3 set of names, defined in Section 4.3 of W3C.REC-css3-color-20110607.

Example

"turquoise", "#ffffff"

>>> from icalendar import Todo
>>> todo = Todo()
>>> todo.color = "green"
>>> print(todo.to_ical())
BEGIN:VTODO
COLOR:green
END:VTODO
property conferences: list[Conference]#

Return the CONFERENCE properties as a list.

Purpose:

This property specifies information for accessing a conferencing system.

Conformance:

This property can be specified multiple times in a “VEVENT” or “VTODO” calendar component.

Description:

This property specifies information for accessing a conferencing system for attendees of a meeting or task. This might be for a telephone-based conference number dial-in with access codes included (such as a tel: URI RFC 3966 or a sip: or sips: URI RFC 3261), for a web-based video chat (such as an http: or https: URI RFC 7230), or for an instant messaging group chat room (such as an xmpp: URI RFC 5122). If a specific URI for a conferencing system is not available, a data: URI RFC 2397 containing a text description can be used.

A conference system can be a bidirectional communication channel or a uni-directional “broadcast feed”.

The “FEATURE” property parameter is used to describe the key capabilities of the conference system to allow a client to choose the ones that give the required level of interaction from a set of multiple properties.

The “LABEL” property parameter is used to convey additional details on the use of the URI. For example, the URIs or access codes for the moderator and attendee of a teleconference system could be different, and the “LABEL” property parameter could be used to “tag” each “CONFERENCE” property to indicate which is which.

The “LANGUAGE” property parameter can be used to specify the language used for text values used with this property (as per Section 3.2.10 of RFC 5545).

Example

The following are examples of this property:

CONFERENCE;VALUE=URI;FEATURE=PHONE,MODERATOR;
 LABEL=Moderator dial-in:tel:+1-412-555-0123,,,654321
CONFERENCE;VALUE=URI;FEATURE=PHONE;
 LABEL=Attendee dial-in:tel:+1-412-555-0123,,,555123
CONFERENCE;VALUE=URI;FEATURE=PHONE;
 LABEL=Attendee dial-in:tel:+1-888-555-0456,,,555123
CONFERENCE;VALUE=URI;FEATURE=CHAT;
 LABEL=Chat room:xmpp:chat-123@conference.example.com
CONFERENCE;VALUE=URI;FEATURE=AUDIO,VIDEO;
 LABEL=Attendee dial-in:https://chat.example.com/audio?id=123456

Get all conferences:

>>> from icalendar import Event
>>> event = Event()
>>> event.conferences
[]

Set a conference:

>>> from icalendar import Event, Conference
>>> event = Event()
>>> event.conferences = [
...     Conference(
...         "tel:+1-412-555-0123,,,654321",
...         feature="PHONE,MODERATOR",
...         label="Moderator dial-in",
...         language="EN",
...     )
... ]
>>> print(event.to_ical())
BEGIN:VEVENT
CONFERENCE;FEATURE="PHONE,MODERATOR";LABEL=Moderator dial-in;LANGUAGE=EN:t
 el:+1-412-555-0123,,,654321
END:VEVENT
property contacts: list[str]#

Contact information associated with the calendar component.

Purpose:

This property is used to represent contact information or alternately a reference to contact information associated with the calendar component.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

In RFC 5545, this property can be specified in a “VEVENT”, “VTODO”, “VJOURNAL”, or “VFREEBUSY” calendar component. In RFC 7953, this property can be specified in a “VAVAILABILITY” amd “VAVAILABLE” calendar component.

Description:

The property value consists of textual contact information. An alternative representation for the property value can also be specified that refers to a URI pointing to an alternate form, such as a vCard RFC 2426, for the contact information.

Example

The following is an example of this property referencing textual contact information:

CONTACT:Jim Dolittle\, ABC Industries\, +1-919-555-1234

The following is an example of this property with an alternate representation of an LDAP URI to a directory entry containing the contact information:

CONTACT;ALTREP="ldap://example.com:6666/o=ABC%20Industries\,
c=US???(cn=Jim%20Dolittle)":Jim Dolittle\, ABC Industries\,
+1-919-555-1234

The following is an example of this property with an alternate representation of a MIME body part containing the contact information, such as a vCard RFC 2426 embedded in a text/ directory media type RFC 2425:

CONTACT;ALTREP="CID:part3.msg970930T083000SILVER@example.com":
 Jim Dolittle\, ABC Industries\, +1-919-555-1234

The following is an example of this property referencing a network resource, such as a vCard RFC 2426 object containing the contact information:

CONTACT;ALTREP="http://example.com/pdi/jdoe.vcf":Jim
 Dolittle\, ABC Industries\, +1-919-555-1234
property description: str | None#

DESCRIPTION provides a more complete description of the calendar component than that provided by the “SUMMARY” property.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

The property can be specified in the “VEVENT”, “VTODO”, “VJOURNAL”, or “VALARM” calendar components. The property can be specified multiple times only within a “VJOURNAL” calendar component.

Description:

This property is used in the “VEVENT” and “VTODO” to capture lengthy textual descriptions associated with the activity.

This property is used in the “VALARM” calendar component to capture the display text for a DISPLAY category of alarm, and to capture the body text for an EMAIL category of alarm.

Examples

The following is an example of this property with formatted line breaks in the property value:

DESCRIPTION:Meeting to provide technical review for "Phoenix"
 design.\nHappy Face Conference Room. Phoenix design team
 MUST attend this meeting.\nRSVP to team leader.
property duration: timedelta#

The duration of the VTODO.

Returns the DURATION property if set, otherwise calculated from start and end. You can set the duration to automatically adjust the end time while keeping start locked.

Setting the duration will: 1. Keep the start time locked (unchanged) 2. Adjust the end time to start + duration 3. Remove any existing DUE property 4. Set the DURATION property

property end: date | datetime#

The end of the todo.

Invalid values raise an InvalidCalendar error. If there is no end, we also raise an IncompleteComponent error.

exclusive = ('DUE', 'DURATION')#
property exdates: list[date | datetime]#

EXDATE defines the list of DATE-TIME exceptions for recurring components.

EXDATE is defined in RFC 5545.

Value Type:

The default value type for this property is DATE-TIME. The value type can be set to DATE.

Property Parameters:

IANA, non-standard, value data type, and time zone identifier property parameters can be specified on this property.

Conformance:

This property can be specified in recurring “VEVENT”, “VTODO”, and “VJOURNAL” calendar components as well as in the “STANDARD” and “DAYLIGHT” sub-components of the “VTIMEZONE” calendar component.

Description:

The exception dates, if specified, are used in computing the recurrence set. The recurrence set is the complete set of recurrence instances for a calendar component. The recurrence set is generated by considering the initial “DTSTART” property along with the “RRULE”, “RDATE”, and “EXDATE” properties contained within the recurring component. The “DTSTART” property defines the first instance in the recurrence set. The “DTSTART” property value SHOULD match the pattern of the recurrence rule, if specified. The recurrence set generated with a “DTSTART” property value that doesn’t match the pattern of the rule is undefined. The final recurrence set is generated by gathering all of the start DATE-TIME values generated by any of the specified “RRULE” and “RDATE” properties, and then excluding any start DATE-TIME values specified by “EXDATE” properties. This implies that start DATE-TIME values specified by “EXDATE” properties take precedence over those specified by inclusion properties (i.e., “RDATE” and “RRULE”). When duplicate instances are generated by the “RRULE” and “RDATE” properties, only one recurrence is considered. Duplicate instances are ignored.

The “EXDATE” property can be used to exclude the value specified in “DTSTART”. However, in such cases, the original “DTSTART” date MUST still be maintained by the calendaring and scheduling system because the original “DTSTART” value has inherent usage dependencies by other properties such as the “RECURRENCE-ID”.

Example

Below, we add an exdate in a list and get the resulting list of exdates.

>>> from icalendar import Event
>>> from datetime import datetime
>>> event = Event()

# Add a list of excluded dates
>>> event.add("EXDATE", [datetime(2025, 4, 28, 16, 5)])
>>> event.exdates
[datetime.datetime(2025, 4, 28, 16, 5)]

Note

You cannot modify the EXDATE value by modifying the result. Use icalendar.cal.Component.add() to add values.

If you want to compute recurrences, have a look at Related projects.

property images: list[Image]#

IMAGE specifies an image associated with the calendar or a calendar component.

Description:

This property specifies an image for an iCalendar object or a calendar component via a URI or directly with inline data that can be used by calendar user agents when presenting the calendar data to a user. Multiple properties MAY be used to specify alternative sets of images with, for example, varying media subtypes, resolutions, or sizes. When multiple properties are present, calendar user agents SHOULD display only one of them, picking one that provides the most appropriate image quality, or display none. The “DISPLAY” parameter is used to indicate the intended display mode for the image. The “ALTREP” parameter, defined in RFC 5545, can be used to provide a “clickable” image where the URI in the parameter value can be “launched” by a click on the image in the calendar user agent.

Conformance:

This property can be specified multiple times in an iCalendar object or in “VEVENT”, “VTODO”, or “VJOURNAL” calendar components.

Note

At the present moment, this property is read-only. If you require a setter, please open an issue or a pull request.

property location: str | None#

The intended venue for the activity defined by a calendar component.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

Since RFC 5545, this property can be specified in “VEVENT” or “VTODO” calendar component. RFC 7953 adds this property to “VAVAILABILITY” and “VAVAILABLE”.

Description:

Specific venues such as conference or meeting rooms may be explicitly specified using this property. An alternate representation may be specified that is a URI that points to directory information with more structured specification of the location. For example, the alternate representation may specify either an LDAP URL RFC 4516 pointing to an LDAP server entry or a CID URL RFC 2392 pointing to a MIME body part containing a Virtual-Information Card (vCard) RFC 2426 for the location.

multiple = ('ATTACH', 'ATTENDEE', 'CATEGORIES', 'COMMENT', 'CONTACT', 'EXDATE', 'RSTATUS', 'RELATED', 'RESOURCES', 'RDATE', 'RRULE')#
name = 'VTODO'#
classmethod new(attendees: list[vCalAddress] | None = None, categories: Sequence[str] = (), classification: CLASS | None = None, color: str | None = None, comments: list[str] | str | None = None, contacts: list[str] | str | None = None, conferences: list[Conference] | None = None, created: date | None = None, description: str | None = None, end: date | datetime | None = None, last_modified: date | None = None, location: str | None = None, organizer: vCalAddress | str | None = None, priority: int | None = None, sequence: int | None = None, stamp: date | None = None, start: date | datetime | None = None, status: STATUS | None = None, summary: str | None = None, uid: str | uuid.UUID | None = None, url: str | None = None)[source]#

Create a new TODO with all required properties.

This creates a new Todo in accordance with RFC 5545.

Parameters:
Returns:

Todo

Raises:

InvalidCalendar – If the content is not valid according to RFC 5545.

Warning

As time progresses, we will be stricter with the validation.

property organizer: vCalAddress | None#

ORGANIZER defines the organizer for a calendar component.

Property Parameters:

IANA, non-standard, language, common name, directory entry reference, and sent-by property parameters can be specified on this property.

Conformance:

This property MUST be specified in an iCalendar object that specifies a group-scheduled calendar entity. This property MUST be specified in an iCalendar object that specifies the publication of a calendar user’s busy time. This property MUST NOT be specified in an iCalendar object that specifies only a time zone definition or that defines calendar components that are not group-scheduled components, but are components only on a single user’s calendar.

Description:

This property is specified within the “VEVENT”, “VTODO”, and “VJOURNAL” calendar components to specify the organizer of a group-scheduled calendar entity. The property is specified within the “VFREEBUSY” calendar component to specify the calendar user requesting the free or busy time. When publishing a “VFREEBUSY” calendar component, the property is used to specify the calendar that the published busy time came from.

The property has the property parameters “CN”, for specifying the common or display name associated with the “Organizer”, “DIR”, for specifying a pointer to the directory information associated with the “Organizer”, “SENT-BY”, for specifying another calendar user that is acting on behalf of the “Organizer”. The non-standard parameters may also be specified on this property. If the “LANGUAGE” property parameter is specified, the identified language applies to the “CN” parameter value.

property priority: int#
Conformance:

This property can be specified in “VEVENT” and “VTODO” calendar components according to RFC 5545. RFC 7953 adds this property to “VAVAILABILITY”.

Description:

This priority is specified as an integer in the range 0 to 9. A value of 0 specifies an undefined priority. A value of 1 is the highest priority. A value of 2 is the second highest priority. Subsequent numbers specify a decreasing ordinal priority. A value of 9 is the lowest priority.

A CUA with a three-level priority scheme of “HIGH”, “MEDIUM”, and “LOW” is mapped into this property such that a property value in the range of 1 to 4 specifies “HIGH” priority. A value of 5 is the normal or “MEDIUM” priority. A value in the range of 6 to 9 is “LOW” priority.

A CUA with a priority schema of “A1”, “A2”, “A3”, “B1”, “B2”, …, “C3” is mapped into this property such that a property value of 1 specifies “A1”, a property value of 2 specifies “A2”, a property value of 3 specifies “A3”, and so forth up to a property value of 9 specifies “C3”.

Other integer values are reserved for future use.

Within a “VEVENT” calendar component, this property specifies a priority for the event. This property may be useful when more than one event is scheduled for a given time period.

Within a “VTODO” calendar component, this property specified a priority for the to-do. This property is useful in prioritizing multiple action items for a given time period.

property rdates: list[tuple[date, None] | tuple[datetime, None] | tuple[datetime, datetime]]#

The RDATE property defines the list of DATE-TIME values for recurring components.

RDATE is defined in RFC 5545. The return value is a list of tuples (start, end).

start can be a datetime.date or a datetime.datetime, with and without timezone.

end is None if the end is not specified and a datetime.datetime if the end is specified.

Value Type:

The default value type for this property is DATE-TIME. The value type can be set to DATE or PERIOD.

Property Parameters:

IANA, non-standard, value data type, and time zone identifier property parameters can be specified on this property.

Conformance:

This property can be specified in recurring “VEVENT”, “VTODO”, and “VJOURNAL” calendar components as well as in the “STANDARD” and “DAYLIGHT” sub-components of the “VTIMEZONE” calendar component.

Description:

This property can appear along with the “RRULE” property to define an aggregate set of repeating occurrences. When they both appear in a recurring component, the recurrence instances are defined by the union of occurrences defined by both the “RDATE” and “RRULE”.

The recurrence dates, if specified, are used in computing the recurrence set. The recurrence set is the complete set of recurrence instances for a calendar component. The recurrence set is generated by considering the initial “DTSTART” property along with the “RRULE”, “RDATE”, and “EXDATE” properties contained within the recurring component. The “DTSTART” property defines the first instance in the recurrence set. The “DTSTART” property value SHOULD match the pattern of the recurrence rule, if specified. The recurrence set generated with a “DTSTART” property value that doesn’t match the pattern of the rule is undefined. The final recurrence set is generated by gathering all of the start DATE-TIME values generated by any of the specified “RRULE” and “RDATE” properties, and then excluding any start DATE-TIME values specified by “EXDATE” properties. This implies that start DATE-TIME values specified by “EXDATE” properties take precedence over those specified by inclusion properties (i.e., “RDATE” and “RRULE”). Where duplicate instances are generated by the “RRULE” and “RDATE” properties, only one recurrence is considered. Duplicate instances are ignored.

Example

Below, we set one RDATE in a list and get the resulting tuple of start and end.

>>> from icalendar import Event
>>> from datetime import datetime
>>> event = Event()

# Add a list of recurrence dates
>>> event.add("RDATE", [datetime(2025, 4, 28, 16, 5)])
>>> event.rdates
[(datetime.datetime(2025, 4, 28, 16, 5), None)]

Note

You cannot modify the RDATE value by modifying the result. Use icalendar.cal.Component.add() to add values.

If you want to compute recurrences, have a look at Related projects.

required = ('UID', 'DTSTAMP')#
property rrules: list[vRecur]#

RRULE defines a rule or repeating pattern for recurring components.

RRULE is defined in RFC 5545. RFC 7529 adds the SKIP parameter icalendar.prop.vSkip.

Property Parameters:

IANA and non-standard property parameters can be specified on this property.

Conformance:

This property can be specified in recurring “VEVENT”, “VTODO”, and “VJOURNAL” calendar components as well as in the “STANDARD” and “DAYLIGHT” sub-components of the “VTIMEZONE” calendar component, but it SHOULD NOT be specified more than once. The recurrence set generated with multiple “RRULE” properties is undefined.

Description:

The recurrence rule, if specified, is used in computing the recurrence set. The recurrence set is the complete set of recurrence instances for a calendar component. The recurrence set is generated by considering the initial “DTSTART” property along with the “RRULE”, “RDATE”, and “EXDATE” properties contained within the recurring component. The “DTSTART” property defines the first instance in the recurrence set. The “DTSTART” property value SHOULD be synchronized with the recurrence rule, if specified. The recurrence set generated with a “DTSTART” property value not synchronized with the recurrence rule is undefined. The final recurrence set is generated by gathering all of the start DATE-TIME values generated by any of the specified “RRULE” and “RDATE” properties, and then excluding any start DATE-TIME values specified by “EXDATE” properties. This implies that start DATE- TIME values specified by “EXDATE” properties take precedence over those specified by inclusion properties (i.e., “RDATE” and “RRULE”). Where duplicate instances are generated by the “RRULE” and “RDATE” properties, only one recurrence is considered. Duplicate instances are ignored.

The “DTSTART” property specified within the iCalendar object defines the first instance of the recurrence. In most cases, a “DTSTART” property of DATE-TIME value type used with a recurrence rule, should be specified as a date with local time and time zone reference to make sure all the recurrence instances start at the same local time regardless of time zone changes.

If the duration of the recurring component is specified with the “DTEND” or “DUE” property, then the same exact duration will apply to all the members of the generated recurrence set. Else, if the duration of the recurring component is specified with the “DURATION” property, then the same nominal duration will apply to all the members of the generated recurrence set and the exact duration of each recurrence instance will depend on its specific start time. For example, recurrence instances of a nominal duration of one day will have an exact duration of more or less than 24 hours on a day where a time zone shift occurs. The duration of a specific recurrence may be modified in an exception component or simply by using an “RDATE” property of PERIOD value type.

Examples

Daily for 10 occurrences:

>>> from icalendar import Event
>>> from datetime import datetime
>>> from zoneinfo import ZoneInfo
>>> event = Event()
>>> event.start = datetime(1997, 9, 2, 9, 0, tzinfo=ZoneInfo("America/New_York"))
>>> event.add("RRULE", "FREQ=DAILY;COUNT=10")
>>> print(event.to_ical())
BEGIN:VEVENT
DTSTART;TZID=America/New_York:19970902T090000
RRULE:FREQ=DAILY;COUNT=10
END:VEVENT
>>> event.rrules
[vRecur({'FREQ': ['DAILY'], 'COUNT': [10]})]

Daily until December 24, 1997:

>>> from icalendar import Event, vRecur
>>> from datetime import datetime
>>> from zoneinfo import ZoneInfo
>>> event = Event()
>>> event.start = datetime(1997, 9, 2, 9, 0, tzinfo=ZoneInfo("America/New_York"))
>>> event.add("RRULE", vRecur({"FREQ": ["DAILY"]}, until=datetime(1997, 12, 24, tzinfo=ZoneInfo("UTC"))))
>>> print(event.to_ical())
BEGIN:VEVENT
DTSTART;TZID=America/New_York:19970902T090000
RRULE:FREQ=DAILY;UNTIL=19971224T000000Z
END:VEVENT
>>> event.rrules
[vRecur({'FREQ': ['DAILY'], 'UNTIL': [datetime.datetime(1997, 12, 24, 0, 0, tzinfo=ZoneInfo(key='UTC'))]})]

Note

You cannot modify the RRULE value by modifying the result. Use icalendar.cal.Component.add() to add values.

If you want to compute recurrences, have a look at Related projects.

property sequence: int#

This property defines the revision sequence number of the calendar component within a sequence of revisions.

Value Type:

INTEGER

Property Parameters:

IANA and non-standard property parameters can be specified on this property.

Conformance:

The property can be specified in “VEVENT”, “VTODO”, or “VJOURNAL” calendar component.

Description:

When a calendar component is created, its sequence number is 0. It is monotonically incremented by the “Organizer’s” CUA each time the “Organizer” makes a significant revision to the calendar component.

The “Organizer” includes this property in an iCalendar object that it sends to an “Attendee” to specify the current version of the calendar component.

The “Attendee” includes this property in an iCalendar object that it sends to the “Organizer” to specify the version of the calendar component to which the “Attendee” is referring.

A change to the sequence number is not the mechanism that an “Organizer” uses to request a response from the “Attendees”. The “RSVP” parameter on the “ATTENDEE” property is used by the “Organizer” to indicate that a response from the “Attendees” is requested.

Recurrence instances of a recurring component MAY have different sequence numbers.

Examples

The following is an example of this property for a calendar component that was just created by the “Organizer”:

>>> from icalendar import Event
>>> event = Event()
>>> event.sequence
0

The following is an example of this property for a calendar component that has been revised 10 different times by the “Organizer”:

>>> from icalendar import Calendar
>>> calendar = Calendar.example("issue_156_RDATE_with_PERIOD_TZID_khal")
>>> event = calendar.events[0]
>>> event.sequence
10
set_duration(duration: timedelta | None, locked: Literal['start', 'end'] = 'start')[source]#

Set the duration of the event relative to either start or end.

Parameters:

  • duration – The duration to set, or None to convert to DURATION property

  • locked – Which property to keep unchanged (‘start’ or ‘end’)

set_end(end: date | datetime, locked: Literal['start', 'duration'] = 'start')[source]#

Set the end of the component, keeping either the start or the duration same.

Parameters:

  • end – The end time to set

  • locked – Which property to keep unchanged (‘start’ or ‘duration’)

set_start(start: date | datetime, locked: Literal['duration', 'end'] | None = None)[source]#

Set the start with explicit locking behavior.

Parameters:

  • start – The start time to set

  • locked – Which property to keep unchanged (‘duration’, ‘end’, or None for auto-detect)

singletons = ('CLASS', 'COLOR', 'COMPLETED', 'CREATED', 'DESCRIPTION', 'DTSTAMP', 'DTSTART', 'GEO', 'LAST-MODIFIED', 'LOCATION', 'ORGANIZER', 'PERCENT-COMPLETE', 'PRIORITY', 'RECURRENCE-ID', 'SEQUENCE', 'STATUS', 'SUMMARY', 'UID', 'URL', 'DUE', 'DURATION')#
property start: date | datetime#

The start of the VTODO.

Invalid values raise an InvalidCalendar. If there is no start, we also raise an IncompleteComponent error.

You can get the start, end and duration of a Todo as follows:

>>> from datetime import datetime
>>> from icalendar import Todo
>>> todo = Todo()
>>> todo.start = datetime(2021, 1, 1, 12)
>>> todo.end = datetime(2021, 1, 1, 12, 30) # 30 minutes
>>> todo.duration  # 1800 seconds == 30 minutes
datetime.timedelta(seconds=1800)
>>> print(todo.to_ical())
BEGIN:VTODO
DTSTART:20210101T120000
DUE:20210101T123000
END:VTODO
property status: StrEnum#

STATUS defines the overall status or confirmation for the calendar component.

Returns:

icalendar.enums.STATUS

The default value is "".

Description:

In a group-scheduled calendar component, the property is used by the “Organizer” to provide a confirmation of the event to the “Attendees”. For example in a “VEVENT” calendar component, the “Organizer” can indicate that a meeting is tentative, confirmed, or cancelled. In a “VTODO” calendar component, the “Organizer” can indicate that an action item needs action, is completed, is in process or being worked on, or has been cancelled. In a “VJOURNAL” calendar component, the “Organizer” can indicate that a journal entry is draft, final, or has been cancelled or removed.

subcomponents: list[Component]#
property summary: str | None#

SUMMARY defines a short summary or subject for the calendar component.

Property Parameters:

IANA, non-standard, alternate text representation, and language property parameters can be specified on this property.

Conformance:

The property can be specified in “VEVENT”, “VTODO”, “VJOURNAL”, or “VALARM” calendar components.

Description:

This property is used in the “VEVENT”, “VTODO”, and “VJOURNAL” calendar components to capture a short, one-line summary about the activity or journal entry.

This property is used in the “VALARM” calendar component to capture the subject of an EMAIL category of alarm.

Examples

The following is an example of this property:

SUMMARY:Department Party
property uid: str#

UID specifies the persistent, globally unique identifier for a component.

We recommend using uuid.uuid4() to generate new values.

Returns:

The value of the UID property as a string or "" if no value is set.

Description:

The “UID” itself MUST be a globally unique identifier. The generator of the identifier MUST guarantee that the identifier is unique.

This is the method for correlating scheduling messages with the referenced “VEVENT”, “VTODO”, or “VJOURNAL” calendar component. The full range of calendar components specified by a recurrence set is referenced by referring to just the “UID” property value corresponding to the calendar component. The “RECURRENCE-ID” property allows the reference to an individual instance within the recurrence set.

This property is an important method for group-scheduling applications to match requests with later replies, modifications, or deletion requests. Calendaring and scheduling applications MUST generate this property in “VEVENT”, “VTODO”, and “VJOURNAL” calendar components to assure interoperability with other group- scheduling applications. This identifier is created by the calendar system that generates an iCalendar object.

Implementations MUST be able to receive and persist values of at least 255 octets for this property, but they MUST NOT truncate values in the middle of a UTF-8 multi-octet sequence.

RFC 7986 states that UID can be used, for example, to identify duplicate calendar streams that a client may have been given access to. It can be used in conjunction with the “LAST-MODIFIED” property also specified on the “VCALENDAR” object to identify the most recent version of a calendar.

Conformance:

RFC 5545 states that the “UID” property can be specified on “VEVENT”, “VTODO”, and “VJOURNAL” calendar components. RFC 7986 modifies the definition of the “UID” property to allow it to be defined in an iCalendar object. RFC 9074 adds a “UID” property to “VALARM” components to allow a unique identifier to be specified. The value of this property can then be used to refer uniquely to the “VALARM” component.

This property can be specified once only.

Security:

RFC 7986 states that UID values MUST NOT include any data that might identify a user, host, domain, or any other security- or privacy-sensitive information. It is RECOMMENDED that calendar user agents now generate “UID” values that are hex-encoded random Universally Unique Identifier (UUID) values as defined in Sections 4.4 and 4.5 of RFC 4122. You can use the uuid module to generate new UUIDs.

Compatibility:

For Alarms, X-ALARMUID is also considered.

Examples

The following is an example of such a property value: 5FC53010-1267-4F8E-BC28-1D7AE55A7C99.

Set the UID of a calendar:

>>> from icalendar import Calendar
>>> from uuid import uuid4
>>> calendar = Calendar()
>>> calendar.uid = uuid4()
>>> print(calendar.to_ical())
BEGIN:VCALENDAR
UID:d755cef5-2311-46ed-a0e1-6733c9e15c63
END:VCALENDAR
property url: str#

A Uniform Resource Locator (URL) associated with the iCalendar object.

Description:

This property may be used in a calendar component to convey a location where a more dynamic rendition of the calendar information associated with the calendar component can be found. This memo does not attempt to standardize the form of the URI, nor the format of the resource pointed to by the property value. If the URL property and Content-Location MIME header are both specified, they MUST point to the same resource.

Conformance:

This property can be specified once in the “VEVENT”, “VTODO”, “VJOURNAL”, or “VFREEBUSY” calendar components. Since RFC 7986, this property can also be defined on a “VCALENDAR”.

Example

The following is an example of this property:

URL:http://example.com/pub/calendars/jsmith/mytime.ics

Submodules#

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