django post_save signals on update

django django-signals
user417918 picture user417918 · Sep 11, 2011 · Viewed 31.4k times · Source

I am trying to set up some post_save receivers similar to the following

@receiver(post_save, sender=Game, dispatch_uid='game_updated')
def game_updated(sender, **kwargs):

    '''DO SOME STUFF HERE'''

    MyPick.objects.filter(week=game.week, team=game.home_team).update(result=home_result)
    MyPick.objects.filter(week=game.week, team=game.away_team).update(result=away_result)


@receiver(post_save, sender=MyPick, dispatch_uid='user_pick_updated')
def update_standings(sender, **kwargs):
    '''DO STUFF'''

The first receiver is getting called correctly after an update on the Game object, however the calls to update on the MyPick object are not causing the second receiver to be called. Does the post_save signal not work on update or am I missing something else here?

Thanks

Answer

Ismail Badawi picture Ismail Badawi · Sep 11, 2011

update() is converted directly to an SQL statement; it doesn't call save() on the model instances, and so the pre_save and post_save signals aren't emitted. If you want your signal receivers to be called, you should loop over the queryset, and for each model instance, make your changes and call save() yourself.

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