id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
37234	bulk_create fails when related objects got PKs later	Filip Sedlák		"This is a regression betwen Django 5.2 and 6.0.

Here's a short reproducer test that, when added to `tests/bulk_create/tests.py` fails with an AssertionError within `bulk_create`.

{{{
    @skipUnlessDBFeature(""can_return_rows_from_bulk_insert"")
    def test_pk_from_related_instance_saved_after_init(self):
        country = Country(name=""Syldavia"", iso_two_letter=""SW"")
        related = RelatedModel(country=country)
        country.save()
        RelatedModel.objects.bulk_create([related])
        self.assertEqual(related.country_id, country.pk)
}}}

Failure:

{{{
  File ""/Users/krab/workspace/django/tests/bulk_create/tests.py"", line 901, in test_pk_from_related_instance_saved_after_init
    RelatedModel.objects.bulk_create([related])
    ^^^^^^^^^^^^^^^
  File ""/Users/krab/workspace/django/django/db/models/manager.py"", line 87, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
    ^^^^^^^
  File ""/Users/krab/workspace/django/django/db/models/query.py"", line 913, in bulk_create
    assert len(returned_columns) == len(objs_without_pk)
    ^^^
}}}

It looks like Django used to support this case intentionally, calling `._prepare_related_fields_for_save(operation_name=""bulk_create"")` within `bulk_create` but a recent change breaks that.

I've never contributed to Django, but I'm willing to work on a fix if you're interested."	Bug	new	Database layer (models, ORM)	6.0	Release blocker			Filip Sedlák Simon Charette	Accepted	0	0	0	0	0	0