Take a look at:
https://github.com/llazzaro/django-scheduler
also available on PyPI:
pypi.python.org/pypi/django-scheduler/
It's very similar to what you have done so far. It handles virtual events
('occurrences') by generating them on the fly for a requested date range.
Individual occurrences can be saved if needed (ie, someone adds a note, or
changes the start/end time of a particular occurrence).
On Friday, 19 September 2014 06:01:48 UTC-7, Sanjay Bhangar wrote:
>
> hey Stodge,
>
> Interesting question :)
>
> My guess is there are probably a number of approaches one can take. Of
> course, processing all your entries in python "on the fly" would
> probably get to be quite an intensive operation.
>
> One possible idea maybe to create a "cache" table of sorts where you
> pre-calculate and store all possible dates for a CalendarEntry.
>
> Something like:
>
> class EventDate(models.Model):
> date = models.DateField(..)
> calendarentry = models.ForeignKey(CalendarEntry)
>
> Then, in the post_save of CalendarEntry, you write some code to
> calculate all possible dates for the event and populate the EventDate
> table. The problem is:
> a> If the CalendarEntry does not have an end_date, you obviously
> cannot calculate all dates until the end of eternity - you would have
> to come up with a reasonable "end date" beyond which queries are not
> possible and only populate EventDate until that point (perhaps
> updating it for the future with a cron job or some such .. )
> b> Generating the EventDates and the associated database INSERTs
> could get quite intensive, especially, for say, a daily event for the
> next 5 years, etc. If that gets to be a problem, you may need to do
> this out of the request-response cycle, using for eg. django-celery.
>
> Once you have that table, of course, querying would be something like
> CalendarEntry.objects.filter(eventdate__date=date) , etc..
>
> This is likely not the most elegant solution - not sure if there's a
> better way to do it, or some efficient way to do the query directly in
> the database without the overhead of maintaining this 'cache' table.
>
> Would love to hear if anyone has an elegant solution to this - else
> what I've outlined above should work, though it doesn't feel 100%
> right, especially the part about needing some arbitrary cut-off date
> to prevent an infinite generation of EventDate entries ..
>
> Please do share what you land up coming up with.
>
> All the best.
> -Sanjay
>
> On Fri, Sep 19, 2014 at 6:13 PM, Stodge <[email protected] <javascript:>>
> wrote:
> > I have the following to model a calendar entry (recurring event). I need
> the
> > ability to retrieve all events from the database between a start and end
> > date. This has to include one off events and also recurring "virtual"
> events
> > that occur because of an event in the database. Do you think this is
> > possible using Django queries? Or do I need to retrieve the objects from
> the
> > DB and then calculate the recurring events in the range in plain python
> > using something like dateutil? I've been racking my brains but I can't
> seem
> > to work out how to do it. Any suggestions appreciated.
> >
> > class CalendarEntry(models.Model):
> >
> > REPEAT_CHOICES = (
> > ('NONE', _('None')),
> > ('DAILY', _('Daily')),
> > ('WEEKDAY', _('Every weekday')),
> > ('WEEKLY', _('Weekly')),
> > ('BIWEEKLY', _('Fortnightly')),
> > ('MONTHLY', _('Monthly')),
> > ('YEARLY', _('Yearly')),
> > )
> >
> > # Mappings between content and an event entry.
> > content_type = models.ForeignKey(ContentType,
> verbose_name='content
> > type')
> > object_id = models.PositiveIntegerField()
> > content_object = generic.GenericForeignKey('content_type',
> 'object_id')
> > field = models.CharField(max_length=64)
> >
> > # Basic event information.
> > start_date = TimestampGMT(blank=True, null=True)
> > end_date = TimestampGMT(blank=True, null=True)
> >
> > # Recurrence information.
> > all_day = models.BooleanField()
> > repeat = models.CharField(max_length=15, choices=REPEAT_CHOICES,
> > default='NEVER')
> > end_repeat = models.DateTimeField(_("end repeat"), null=True,
> > blank=True)
> >
> >
> >
> >
> >
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