icalendar.cal.alarm module#

RFC 5545 VALARM component.

class icalendar.cal.alarm.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.

Example

The following example creates an alarm which uses an audio file from an FTP server.

>>> from icalendar import Alarm
>>> alarm = Alarm.example()
>>> print(alarm.to_ical().decode())
BEGIN:VALARM
ACTION:AUDIO
ATTACH;FMTTYPE=audio/basic:ftp://example.com/pub/sounds/bell-01.aud
DURATION:PT15M
REPEAT:4
TRIGGER;VALUE=DATE-TIME:19970317T133000Z
END:VALARM

Set keys to upper for initial dict.

property ACKNOWLEDGED: datetime | None#

The ACKNOWLEDGED property. datetime in UTC

All values will be converted to a datetime in UTC. The UTC datetime at which this alarm was last sent or acknowledged.

Defined in RFC 9074. Setting this property allows calendar clients to dismiss or suppress an alarm across multiple devices. Once set to a value greater than or equal to the alarm's computed trigger time, conforming clients will not re-fire the alarm.

Returns None when no acknowledgment has been recorded.

Example

Mark an alarm as acknowledged at the current time.

>>> from datetime import timezone, datetime
>>> from icalendar import Alarm
>>> alarm = Alarm()
>>> alarm.ACKNOWLEDGED = datetime(2024, 1, 15, 10, 0, 0, tzinfo=timezone.utc)
>>> alarm.ACKNOWLEDGED
datetime.datetime(2024, 1, 15, 10, 0, tzinfo=...)

See also

TRIGGER_RELATED, DURATION, REPEAT

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.

property TRIGGER_RELATED: str#

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

Create new instance of Triggers(start, end, absolute)

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.

classmethod example(name='example')[source]#

Return the alarm example with the given name.

Return type:: Alarm

inclusive: ClassVar[tuple[str] | tuple[tuple[str, str]]] = (('DURATION', 'REPEAT'), ('SUMMARY', 'ATTENDEE'))#

These properties are inclusive.

In other words, if the first property in the tuple occurs, then the second one must also occur.

Example

('duration', 'repeat')

multiple: ClassVar[tuple[()]] = ('ATTENDEE', 'ATTACH', 'RELATED-TO')#: These properties may occur more than once.

name: ClassVar[str | None] = 'VALARM'#

The name of the component.

This is defined in each component class.

Example

>>> from icalendar import Calendar
>>> cal = Calendar.new()
>>> cal.name
'VCALENDAR'

classmethod new(attendees=None, concepts=None, description=None, links=None, refids=None, related_to=None, summary=None, uid=None)[source]#

Create a new alarm with all required properties.

This creates a new Alarm in accordance with RFC 5545.

Parameters:

attendees (list[vCalAddress] | None) – The attendees of the alarm.
concepts (list[vUri | str] | str | vUri | None) – The concepts of the alarm.
description (str | None) – The description of the alarm.
links (str | vUri | vUid | vXmlReference | None | list[str | vUri | vUid | vXmlReference]) – The links of the alarm.
refids (list[str] | str | None) – refids of the alarm.
related_to (None | str | vText | vUri | vUid | list[str | vText | vUri | vUid]) – related_to of the alarm.
summary (str | None) – The summary of the alarm.
uid (str | UUID | None) – 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: ClassVar[tuple[()]] = ('ACTION', 'TRIGGER')#: These properties are required.

singletons: ClassVar[tuple[()]] = ('ATTACH', 'ACTION', 'DESCRIPTION', 'SUMMARY', 'TRIGGER', 'DURATION', 'REPEAT', 'UID', 'PROXIMITY', 'ACKNOWLEDGED')#: These properties must appear only once.

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