recurring-ical-events 3.3.3

at(a_date)

You can get all events which take place at a_date. A date can be a year, e.g. 2023, a month of a year e.g. January in 2023 (2023, 1), a day of a certain month e.g. (2023, 1, 1), an hour e.g. (2023, 1, 1, 0), a minute e.g. (2023, 1, 1, 0, 0), or second as well as a datetime.date object and datetime.datetime.

The start and end are inclusive. As an example: if an event is longer than one day it is still included if it takes place at a_date.

>>> import datetime

# save the query object for the calendar
>>> query = recurring_ical_events.of(a_calendar)
>>> len(query.at(2023))                      # a year - 2023 has 12 events happening
12
>>> len(query.at((2023,)))                   # a year
12
>>> len(query.at((2023, 1)))                 # January in 2023 - only one event is in January
1
>>> len(query.at((2023, 1, 1)))              # the 1st of January in 2023
0
>>> len(query.at("20230101"))                # the 1st of January in 2023
0
>>> len(query.at((2023, 1, 1, 0)))           # the first hour of the year 2023
0
>>> len(query.at((2023, 1, 1, 0, 0)))        # the first minute in 2023
0
>>> len(query.at(datetime.date(2023, 1, 1))) # the first day in 2023
0
>>> len(query.at(datetime.date.today()))     # today
0
>>> len(query.at(datetime.datetime.now()))   # this exact second
0

The resulting events are a list of icalendar events, see below.

between(start, end)

between(start, end) returns all events happening between a start and an end time. Both arguments can be datetime.datetime, datetime.date, tuples of numbers passed as arguments to datetime.datetime or strings in the form of %Y%m%d (yyyymmdd) and %Y%m%dT%H%M%SZ (yyyymmddThhmmssZ). Additionally, the end argument can be a datetime.timedelta to express that the end is relative to the start. For examples of arguments, see at(a_date) above.

>>> query = recurring_ical_events.of(a_calendar)

# What happens in 2016, 2017 and 2018?
>>> events = recurring_ical_events.of(a_calendar).between(2016, 2019)
>>> len(events) # quite a lot is happening!
39

The resulting events are in a list of icalendar events, see below.

after(earliest_end)

You can retrieve events that happen after a time or date using after(earliest_end). Events that are happening during the earliest_end are included in the iteration.

>>> earlierst_end = 2023
>>> for i, event in enumerate(query.after(earlierst_end)):
...     print(f"{event['SUMMARY']} ends {event['DTEND'].dt}") # all dates printed are after January 1st 2023
...     if i > 10: break  # we might get endless events and a lot of them!
Repair Café ends 2023-01-07 17:00:00+01:00
Repair Café ends 2023-02-04 17:00:00+01:00
Repair Café ends 2023-03-04 17:00:00+01:00
Repair Café ends 2023-04-01 17:00:00+02:00
Repair Café ends 2023-05-06 17:00:00+02:00
Repair Café ends 2023-06-03 17:00:00+02:00
Repair Café ends 2023-07-01 17:00:00+02:00
Repair Café ends 2023-08-05 17:00:00+02:00
Repair Café ends 2023-09-02 17:00:00+02:00
Repair Café ends 2023-10-07 17:00:00+02:00
Repair Café ends 2023-11-04 17:00:00+01:00
Repair Café ends 2023-12-02 17:00:00+01:00

all()

If you wish to iterate over all occurrences of the components, then you can use all(). Since a calendar can define a huge amount of recurring entries, this method generates them and forgets them, reducing memory overhead.

This example shows the first event that takes place in the calendar:

>>> first_event = next(query.all()) # not all events are generated
>>> print(f"The first event is {first_event['SUMMARY']}")
The first event is Weihnachts Repair-Café

count()

You can count occurrences of events and other components using count().

>>> number_of_TODOs = recurring_ical_events.of(a_calendar, components=["VTODO"]).count()
>>> print(f"You have {number_of_TODOs} things to do!")
You have 0 things to do!

>>> number_of_journal_entries = recurring_ical_events.of(a_calendar, components=["VJOURNAL"]).count()
>>> print(f"There are {number_of_journal_entries} journal entries in the calendar.")
There are 0 journal entries in the calendar.

However, this can be very costly!

events as list - at() and between()

The result of both between(start, end) and at(a_date) is a list of icalendar events. By default, all attributes of the event with repetitions are copied, like UID and SUMMARY. However, these attributes may differ from the source event:

• DTSTART which is the start of the event instance. (always present)

• DTEND which is the end of the event instance. (always present)

• RDATE, EXDATE, RRULE are the rules to create event repetitions. They are not included in repeated events, see Issue 23. To change this, use of(calendar, keep_recurrence_attributes=True).

Generator - after() and all()

If the resulting components are ordered when after(earliest_end) or all() is used. The result is an iterator that returns the events in order.

for event in recurring_ical_events.of(an_icalendar_object).after(datetime.datetime.now()):
    print(event["DTSTART"]) # The start is ordered

Different Components, not just Events

By default the recurring_ical_events only selects events as the name already implies. However, there are different components available in a calendar. You can select which components you like to have returned by passing components to the of function:

of(a_calendar, components=["VEVENT"])

Here is a template code for choosing the supported types of components:

>>> query_events = recurring_ical_events.of(a_calendar)
>>> query_journals = recurring_ical_events.of(a_calendar, components=["VJOURNAL"])
>>> query_todos = recurring_ical_events.of(a_calendar, components=["VTODO"])
>>> query_all = recurring_ical_events.of(a_calendar, components=["VTODO", "VEVENT", "VJOURNAL"])

If a type of component is not listed here, it can be added. Please create an issue for this in the source code repository.

For further customization, please refer to the section on how to extend the default functionality.

Speed

If you use between() or at() several times, it is faster to re-use the object coming from of().

>>> query = recurring_ical_events.of(a_calendar)
>>> events_of_day_1 = query.at((2019, 2, 1))
>>> events_of_day_2 = query.at((2019, 2, 2))
>>> events_of_day_3 = query.at((2019, 2, 3))

# ... and so on

Skip bad formatted ical events

Some events may be badly formatted and therefore cannot be handled by recurring-ical-events. Passing skip_bad_series=True as of() argument will totally skip theses events.

# Create a calendar that contains broken events.
>>> calendar_file = CALENDARS / "bad_rrule_missing_until_event.ics"
>>> calendar_with_bad_event = icalendar.Calendar.from_ical(calendar_file.read_bytes())

 # By default, broken events result in errors.
>>> recurring_ical_events.of(calendar_with_bad_event, skip_bad_series=False).count()
Traceback (most recent call last):
  ...
recurring_ical_events.BadRuleStringFormat: UNTIL parameter is missing: FREQ=WEEKLY;BYDAY=TH;WKST=SU;UNTL=20191023

# With skip_bad_series=True we skip the series that we cannot handle.
>>> recurring_ical_events.of(calendar_with_bad_event, skip_bad_series=True).count()
0

Extending recurring-ical-events

All the functionality of recurring-ical-events can be extended and modified. To understand where to extend, have a look at the Architecture.

The first place for extending is the collection of components. Components are collected into a Series. A series belongs together because all components have the same UID. In this example, we collect one VEVENT which matches a certain UID:

>>> from recurring_ical_events import SelectComponents, EventAdapter, Series
>>> from icalendar.cal import Component
>>> from typing import Sequence

# create the calendar
>>> calendar_file = CALENDARS / "machbar_16_feb_2019.ics"
>>> machbar_calendar = icalendar.Calendar.from_ical(calendar_file.read_bytes())

# Create a collector of components that searches for an event with a specific UID
>>> class CollectOneUIDEvent(SelectComponents):
...     def __init__(self, uid:str) -> None:
...         self.uid = uid
...     def collect_series_from(self, source: Component, suppress_errors: tuple) -> Sequence[Series]:
...         components : list[Component] = []
...         for component in source.walk("VEVENT"):
...             if component.get("UID") == self.uid:
...                 components.append(EventAdapter(component))
...         return [Series(components)] if components else []

# collect only one UID: 4mm2ak3in2j3pllqdk1ubtbp9p@google.com
>>> one_uid = CollectOneUIDEvent("4mm2ak3in2j3pllqdk1ubtbp9p@google.com")
>>> uid_query = recurring_ical_events.of(machbar_calendar, components=[one_uid])
>>> uid_query.count()  # the event has no recurrence and thus there is only one
1

Several ways of extending the functionality have been created to override internals. These can be subclassed or composed.

Below, you can choose to collect all components. Subclasses can be created for the Series and the Occurrence.

>>> from recurring_ical_events import AllKnownComponents, Series, Occurrence

# we create a calendar with one event
>>> calendar_file = CALENDARS / "one_event.ics"
>>> one_event = icalendar.Calendar.from_ical(calendar_file.read_bytes())

# You can override the Occurrence and Series classes for all computable components
>>> select_all_known = AllKnownComponents(series=Series, occurrence=Occurrence)
>>> select_all_known.names  # these are the supported types of components
['VEVENT', 'VTODO', 'VJOURNAL']
>>> query_all_known = recurring_ical_events.of(one_event, components=[select_all_known])

# There should be exactly one event.
>>> query_all_known.count()
1

This example shows that the behavior for specific types of components can be extended. Additional to the series, you can change the ComponentAdapter that provides a unified interface for all the components with the same name (VEVENT for example).

>>> from recurring_ical_events import ComponentsWithName, EventAdapter, JournalAdapter, TodoAdapter

# You can also choose to select only specific subcomponents by their name.
# The default arguments are added to show the extensibility.
>>> select_events =   ComponentsWithName("VEVENT",   adapter=EventAdapter,   series=Series, occurrence=Occurrence)
>>> select_todos =    ComponentsWithName("VTODO",    adapter=TodoAdapter,    series=Series, occurrence=Occurrence)
>>> select_journals = ComponentsWithName("VJOURNAL", adapter=JournalAdapter, series=Series, occurrence=Occurrence)

# There should be one event happening and nothing else
>>> recurring_ical_events.of(one_event, components=[select_events]).count()
1
>>> recurring_ical_events.of(one_event, components=[select_todos]).count()
0
>>> recurring_ical_events.of(one_event, components=[select_journals]).count()
0

So, if you would like to modify all events that are returned by the query, you can do that subclassing the Occurrence class.

# This occurence changes adds a new attribute to the resulting events
>>> class MyOccurrence(Occurrence):
...     """An occurrence that modifies the component."""
...     def as_component(self, keep_recurrence_attributes: bool) -> Component:
...         """Return a shallow copy of the source component and modify some attributes."""
...         component = super().as_component(keep_recurrence_attributes)
...         component["X-MY-ATTRIBUTE"] = "my occurrence"
...         return component
>>> query = recurring_ical_events.of(one_event, components=[ComponentsWithName("VEVENT", occurrence=MyOccurrence)])
>>> event = next(query.all())
>>> event["X-MY-ATTRIBUTE"]
'my occurrence'

This library allows extension of functionality during the selection of components to calculate using these classes:

• ComponentsWithName - for components of a certain name

• AllKnownComponents - for all components known

• SelectComponents - the interface to provide

You can further customize behaviour by subclassing these:

• ComponentAdapter such as EventAdapter, JournalAdapter or TodoAdapter.

• Series

• Occurrence

• CalendarQuery

Version Fixing

If you use this library in your code, you may want to make sure that updates can be received but they do not break your code. The version numbers are handeled this way: a.b.c example: 0.1.12

• c is changed for each minor bug fix.

• b is changed whenever new features are added.

• a is changed when the interface or major assumptions change that may break your code.

So, I recommend to version-fix this library to stay with the same a while b and c can change.

Code style

Please install pre-commit before git commit. It will ensure that the code is formatted and linted as expected using ruff.

pre-commit install

Testing

This project’s development is driven by tests. Tests assure a consistent interface and less knowledge lost over time. If you like to change the code, tests help that nothing breaks in the future. They are required in that sense. Example code and ics files can be transferred into tests and speed up fixing bugs.

You can view the tests in the test folder. If you have a calendar ICS file for which this library does not generate the desired output, you can add it to the test/calendars folder and write tests for what you expect. If you like, open an issue first, e.g. to discuss the changes and how to go about it.

To run the tests, we use tox. tox tests all different Python versions which we want to be compatible to.

pip3 install tox

To run all the tests:

tox

To run the tests in a specific Python version:

tox -e py39