Calling .delete() on a queryset doesn't delete related objects.

[אורי]

I created a new test and it had users and I deleted them:

User.objects.all().exclude(pk=self.user_1.pk).delete()

The User model has related models with on_delete=models.CASCADE which should be deleted as well.

But in my test, I got this exception:

======================================================================
ERROR: test_like_list_views_titles_with_empty_lists (speedy.match.likes.tests.test_views.LikeListViewsEnglishTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "env\lib\site-packages\django\db\backends\utils.py", line 84, in _execute
    return self.cursor.execute(sql)
psycopg2.errors.ForeignKeyViolation: insert or update on table "net_accounts_siteprofile" violates foreign key constraint "net_accounts_sitepro_user_id_c96775a1_fk_accounts_"
DETAIL:  Key (user_id)=(403828609159078) is not present in table "accounts_user".


The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "env\lib\site-packages\django\test\testcases.py", line 274, in __call__
    self._post_teardown()
  File "env\lib\site-packages\django\test\testcases.py", line 1009, in _post_teardown
    self._fixture_teardown()
  File "env\lib\site-packages\django\test\testcases.py", line 1177, in _fixture_teardown
    connections[db_name].check_constraints()
  File "env\lib\site-packages\django\db\backends\postgresql\base.py", line 276, in check_constraints
    self.cursor().execute('SET CONSTRAINTS ALL IMMEDIATE')
  File "env\lib\site-packages\django\db\backends\utils.py", line 68, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "env\lib\site-packages\django\db\backends\utils.py", line 77, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "env\lib\site-packages\django\db\backends\utils.py", line 86, in _execute
    return self.cursor.execute(sql, params)
  File "env\lib\site-packages\django\db\utils.py", line 90, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "env\lib\site-packages\django\db\backends\utils.py", line 84, in _execute
    return self.cursor.execute(sql)
django.db.utils.IntegrityError: insert or update on table "net_accounts_siteprofile" violates foreign key constraint "net_accounts_sitepro_user_id_c96775a1_fk_accounts_"
DETAIL:  Key (user_id)=(403828609159078) is not present in table "accounts_user".


----------------------------------------------------------------------
Ran 1 test in 7.425s

I think this exception is because the users I deleted. net_accounts_siteprofile refers to the SiteProfile model which should be deleted when deleting a user by on_delete=models.CASCADE .

I checked and eventually I found out that changing:

User.objects.all().exclude(pk=self.user_1.pk).delete()

To:

for user in User.objects.all().exclude(pk=self.user_1.pk):
    user.delete()

Fixes the problem. But I expected related objects to be deleted by the first query too. Does it mean I can't safely delete users in bulk by .delete()? And if it does, how do I disable it so trying to delete users in bulk will raise an exception?

I would like either to fix the queryset bulk .delete() method to delete related objects too, or to completely disable bulk deletions in Django. Is there a simple way to define a manager which doesn't have this bulk delete feature?

[אורי]

Hi,

Since it's open source you can see the code. I created a branch with the failing test. You can see the test on ​https://github.com/speedy-net/speedy-net/blob/uri_temp_temp_branch_2020-05-18_a/speedy/match/likes/tests/test_views.py#L366-L411 and the commit who causes it to fail on ​https://github.com/speedy-net/speedy-net/commit/d91bd29d465149ede7ff906e0982b21d6c4a712f . You can check the failing tests on Travis CI ​https://travis-ci.org/github/speedy-net/speedy-net/builds/688212117 and the passing tests without this commit on ​https://travis-ci.org/github/speedy-net/speedy-net/builds/688210140 .

[Mariusz Felisiak]

Thanks for this ticket, however I cannot reproduce this issue, everything works for me with two simple models (I used OneToOneField like in your models):

class A(models.Model):
    pass

class B(models.Model):
    a = models.OneToOneField(A, primary_key=True, on_delete=models.CASCADE, related_name='other_name')                                                                                                                                                  

it's hard to tell why your tests failed because models are quite complicated. Please use one of support channel.

Closing per TicketClosingReasons/UseSupportChannels.

[אורי]

Eventually I decided to disable the .delete() method in all querysets in model managers in my project and I don't allow to delete objects from querysets any more. Any delete command should be executed on the object itself. [ ​commit ]

It would be nice to have a settings in Django that does this - disable the .delete() method in all querysets.