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
pre_save. This is sent at the beginning of a model's save() method. Arguments sent with this signal: sender.
For the uninitiated, signals are synchronously (this will be important later) firing events that trigger handlers. There are a few common built in ones, we'll be discussing post_save and pre_save signals that are triggered whenever a Django model is saved.
Sending signals There are two ways to send signals in Django. To send a signal, call either Signal. send() (all built-in signals use this) or Signal. send_robust() .
Only use signals to avoid introducing circular dependencies. If you have two apps, and one app wants to trigger behaviour in an app it already knows about, don't use signals. The app should just import the function it needs and call it directly.
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.
Just one more thing to @Ismali Badawi's answer.
This calls post_save
user = User.objects.get(id=1) user.username='edited_username' user.save()
This does not call post_save
User.objects.filter(id=1).update(username='edited_username')
In the code,
from django.db.models.signals import post_save @receiver(post_save, sender=User) def do_something_when_user_updated(sender, instance, created, **kwargs): if not created: # User object updated user_obj = instance pass
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