keep_parents=True does not exclude proxy neighbors

[Vladimir]

class Foo(Model):
    pass

class Bar(Foo):
    pass

class Baz(Foo):
    class Meta:
        proxy = True

class BazItem(Model):
    baz = ForeignKey(to=Baz, on_delete=CASCADE)

...

bar = Bar.objects.create()
baz = Baz.objects.all().first()
BazItem.objects.create(baz=baz)
assert BazItem.objects.all().count() == 1
bar.delete(keep_parents=True)
assert BazItem.objects.all().count() == 0

seems django.db.models.deletion.Collector.collect

if keep_parents and related.model in model._meta.all_parents:
    continue

should use concrete_model

[Sarah Boyce]

I'm not 100% sure what you're trying to show here:

foo_parent = bar.foo_ptr
bar.delete(keep_parents=True)
foo_parent.refresh_from_db()
assert foo

So the parent is kept. That the BazItem is deleted is due to the CASCADE delete. To me, this looks like it's by design.

[Vladimir]

Replying to Sarah Boyce:

I'm not 100% sure what you're trying to show here:

foo_parent = bar.foo_ptr
bar.delete(keep_parents=True)
foo_parent.refresh_from_db()
assert foo

So the parent is kept. That the BazItem is deleted is due to the CASCADE delete. To me, this looks like it's by design.

BazItem referencing to Baz(Foo table), and deleting bar instance with keep_parents=True should delete only Bar table row, but delete BazItem too

If the Baz model also uses table inheritance, deleting bar with keep_parents=True will not affect the BazItem table. Regardless of where the BazItem will refer to, Foo or Baz

[Sarah Boyce]

Apologies, I read it wrong and thought Baz inherited from Bar.
I can replicate, I agree this is a bug

[Sarah Boyce <42296566+sarahboyce@…>]

In 748551f:

Fixed #36264 -- Excluded proxy neighbors of parents from deletion collection when keep_parents=True.

Signed-off-by: saJaeHyukc <wogur981208@…>

[Sarah Boyce <42296566+sarahboyce@…>]

In e0f328d7:

[6.0.x] Fixed #36264 -- Excluded proxy neighbors of parents from deletion collection when keep_parents=True.

Signed-off-by: saJaeHyukc <wogur981208@…>

Backport of 748551fea0b4e37231203a063356572a47e09efb from main.