On Tue, May 11, 2010 at 8:27 PM, Daniel Roseman <dan...@roseman.org.uk>wrote:
> On May 11, 7:08 pm, Malcolm Box <malcolm....@gmail.com> wrote: > > Hi, > > > > I've run into a weird bug that has me scratching my head - I'm seeing > > inconsistent results from a queryset between various apache processes and > > the django shell. I.e. sometimes a GET gives me the right response (as > it > > hits a "correct" Apache instance) and other times it gives a wrong > > response. Restarting Apache causes problem to go away, but it resurfaces > > later. > > > > I have a Poll class which has a start_time and an end_time, both of which > > are optional, plus an enabled field. A poll is considered active if it's > > enabled, and if it has a start_time then now > start_time, and if it has > an > > end_time then now < end_time. > > > > What I'm seeing is that sometimes polls with a start_time that is before > now > > are not showing up in the responses when I do a series of GETs. So e.g. > > first GET - shows poll, second one - doesn't show, third - doesn't, > fourth - > > does and so on. > > > > From a fresh python shell, the Poll.objects.active() call always gives > the > > right results. > > > > The code in question is: > > > > class PollManager(models.Manager): > > def active(self): > > qs = super(PollManager, > self).get_query_set().filter(enabled=True) > > q_start = Q(start_time__isnull=True) | > > Q(start_time__lte=datetime.datetime.now()) > > q_end = Q(end_time__isnull=True) | > > Q(end_time__gte=datetime.datetime.now()) > > return qs.filter(q_start,q_end) > > > > Where the models are is: > > > > class Event(models.Model): > > enabled = models.BooleanField() # automatic default false > > .... other fields > > > > class Poll(models.Model): > > event = models.ForeignKey(Event, db_index=True) > > enabled = models.BooleanField() # automatic default false > > start_time = models.DateTimeField(blank=True, null=True, > help_text="Time > > to enable this poll (optional)") > > end_time = models.DateTimeField(blank=True, null=True, > help_text="Time > > to close this poll (optional)") > > > > objects = PollManager() > > > > The view logic is basically: > > > > def view_polls(request, event_id): > > filtered_set = self.queryset._clone() # Queryset is > > Poll.objects.active().filter(event__enabled = True) > > filtered_set = filtered_set.filter(event__id=event_id) > > return render_to_response(template, filtered_set) > > > > (this has been elided and adapted - original code is using > django-rest-api, > > JSON responder etc. But the call boils down to this) > > > > I'm confused as to what the problem could be - any clues? > > > > Cheers, > > > > Malcolm > > I'd like to see how the queryset is assigned to `self`. My suspicion > would be that the arguments are being preserved across requests - when > it's first instantiated, it correctly uses the current time to filter, > but on subsequent calls it is still using the time as of the first > request. > The queryset is being initialised in the construction of a callable which is then used for the view. So yes, it probably is only being initialised once on server startup. Thank you! Still testing the fix, but I think this will fix it. Cheers, Malcolm -- You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-us...@googlegroups.com. To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/django-users?hl=en.
