[Bug] post_deleted listener raise an Exception on user delete Cascade

[DylannCordel]

Hi,

When we delete an user, cascade delete will try to delete posts and profile too. When post are deleted, post_delete signal is sent and post_deleted callback is called. This callback update the post_count of the author's profile. Do do that, it call util.get_pybb_profile(instance.user) and here is the problem :

With the default Profile which has an AutoOneToOneField relation with the user, the profile is re-created. So, there is not any error, but once the user and all its posts are deleted, the profile still exists.

With a custom Profile wich use a classic OneToOneField, a DoesNotExists exception is raised because profile has already be deleted.

This is an other good point for #54 : use custom signals instead of default models signals : post_deleted callback should not be called when we batch delete posts (like cascade or via api for eg.). Furthermore, if I delete 1 000 posts from one user, his post_count will be recalculated 1 000 times (so 2 000 extra SQL queries will be performed instead of one)

[DylannCordel]

I just create a pull request with a temporary patch and tests to check this error does not exist anymore.

For users which have the same problem, you can also ugly patch you own code :

#your models.py

from django.contrib.auth import get_user_model
User = get_user_model()

def user_delete(self, *args, **kwargs):
    from pybb.models import Post
    Post.objects.filter(user=self).delete()
    super(User, self).delete(*args, **kwargs)

delete on queryset "only" perform a SQL Delete (does not call delete method for each instances, so post_deleted is never called).