django-eventtools 1.0.3
Recurring event tools for django
License: BSD License

django-eventtools is a lightweight library designed to handle repeating
and one-off event occurrences for display on a website.

`Circle
CI <https://circleci.com/gh/gregplaysguitar/django-eventtools>`__
`codecov <https://codecov.io/gh/gregplaysguitar/django-eventtools>`__
`Latest Version <https://pypi.python.org/pypi/django-eventtools/>`__

Installation
------------

Download the source from https://pypi.python.org/pypi/django-eventtools/
and run ``python setup.py install``, or:

::

   > pip install django-eventtools

Django 1.8 or higher is required.

Setup
-----

Given the following models:

.. code:: python

   from django.db import models

   from eventtools.models import BaseEvent, BaseOccurrence


   class MyEvent(BaseEvent):
       title = models.CharField(max_length=100)


   class MyOccurrence(BaseOccurrence):
       event = models.ForeignKey(MyEvent)

Usage
-----

Create a sample event & occurrences

::

   >>> from datetime import datetime
   >>> from myapp.models import MyEvent
   >>> event = MyEvent.objects.create(title='Test event')
   >>> once_off = MyOccurrence.objects.create(
           event=event,
           start=datetime(2016, 1, 1, 12, 0),
           end=datetime(2016, 1, 1, 2, 0))
   >>> christmas = MyOccurrence.objects.create(
           event=event,
           start=datetime(2015, 12, 25, 7, 0),
           end=datetime(2015, 12, 25, 22, 0),
           repeat='RRULE:FREQ=YEARLY')
   >>> daily = MyOccurrence.objects.create(
           event=event,
           start=datetime(2016, 1, 1, 7, 0),
           end=datetime(2016, 1, 1, 8, 0),
           repeat='RRULE:FREQ=DAILY')

Event and Occurrence instances, and their associated querysets, all
support the ``all_occurrences`` method, which takes two optional
arguments - ``from_date`` and ``to_date``, which may be dates or
datetimes. ``from_date`` and ``to_date`` default to ``None``. The method
returns a python generator yielding tuples in the format
``(start, end, instance)`` - for example:

::

   >>> MyEvent.objects.all().all_occurrences()
   >>> event.all_occurrences(from_date=datetime(2015, 1, 1, 10, 0))
   >>> event.occurrence_set.all().all_occurrences(to_date=date(2016, 1, 1))
   >>> occurrence.all_occurrences(from_date=date(2016, 1, 1),
                                  to_date=date(2016, 12, 31))

``instance`` is an instance of the corresponding BaseOccurrence
subclass.

A ``next_occurrence`` method is also provided, taking the same
arguments, but returning a single occurrence tuple.

::

   >>> event.next_occurrence()
   >>> event.next_occurrence(from_date=date(2016, 1, 1))

The method ``first_occurrence`` also returns a single occurrence tuple,
but takes no arguments.

Queryset filtering
~~~~~~~~~~~~~~~~~~

Event and Occurrence querysets can be filtered, but due to uncertainty
with repetitions, ``from_date`` filtering is only an approximation
(whereas ``to_date`` filtering is accurate). If you need a queryset
filtered exactly, pass ``exact=True`` - this will filter using generated
occurrences but still return a queryset - but be careful with this as it
may be very slow and/or CPU-hungry. For example

::

   >>> MyEvent.objects.for_period(from_date=date(2015, 1, 1),
                                to_date=date(2015, 12, 31))
   >>> event.occurrence_set.for_period(from_date=date(2015, 1, 1), exact=True)

Sorting querysets
~~~~~~~~~~~~~~~~~

Event and Occurrence querysets can also be sorted by their next
occurrence using the ``sort_by_next`` method. By default this sorts
instances by their first occurrence; the optional ``from_date`` argument
will sort by the next occurrence after ``from_date``. For example

::

   >>> MyEvent.objects.all().sort_by_next()
   >>> event.occurrence_set.for_period(from_date=date(2015, 1, 1)) \
   >>>      .sort_by_next(date(2015, 1, 1))

Note that this method returns a sorted list, not a queryset.

Custom repeat intervals
-----------------------

Occurrences can repeat using any interval that can be expressed as an
`rrulestr <https://labix.org/python-dateutil#head-e987b581aebacf25c7276d3e9214385a12a091f2>`__.
To customise the available options, set ``EVENTTOOLS_REPEAT_CHOICES`` in
your django settings. The default value is

.. code:: python

   EVENTTOOLS_REPEAT_CHOICES = (
       ("RRULE:FREQ=DAILY", 'Daily'),
       ("RRULE:FREQ=WEEKLY", 'Weekly'),
       ("RRULE:FREQ=MONTHLY", 'Monthly'),
       ("RRULE:FREQ=YEARLY", 'Yearly'),
   )

Set ``EVENTTOOLS_REPEAT_CHOICES = None`` to make repeat a plain-text
field.

Occurrence cancellations or modifications
-----------------------------------------

Cancelling or modifying a single occurrence repetition is not currently
supported, but can be implemented by overriding a couple of methods. For
example, the following allows cancellations or one-off modifications to
the start time of a repetition:

.. code:: python

   from eventtools.models import (BaseEvent, BaseOccurrence, default_naive)
   from django.db import models


   class MyEvent(BaseEvent):
       pass


   class MyEventOccurrence(BaseOccurrence):
       event = models.ForeignKey(MyEvent)
       overrides = models.ManyToManyField('MyEventOccurrenceOverride', blank=True)

       def get_repeater(self):
           rule = super().get_repeater()  # gets rruleset from parent method
           ruleset.rrule(rule)
           for override in self.overrides.all():
               ruleset.exdate(default_naive(override.start))  # remove occurrence
               if override.modified_start:  # reschedule occurrence if defined
                   ruleset.rdate(default_naive(override.modified_start))
           return ruleset


   class MyEventOccurrenceOverride(models.Model):
       start = models.DateTimeField()  # must match targeted repetition exactly
       # new start, leave blank to cancel
       modified_start = models.DateTimeField(blank=True, null=True)  

Note that start times must match exactly, so if the MyEventOccurrence
start is changed, any previously-matching overrides will no longer be
applied.

Running tests
-------------

Use tox (https://pypi.python.org/pypi/tox):

::

   > pip install tox
   > cd path-to/django-eventtools
   > tox