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
33809	ValueError in migrations using apps.get_model() for a ForeignKey.	Jesse	nobody	"Django 4.0.5, Python 3.9.5

I believe this is a regression of https://code.djangoproject.com/ticket/24282

Snippet of the stack trace:

{{{
  File ""/home/.../venv/lib/python3.9/site-packages/django/db/models/manager.py"", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File ""/home/.../venv/lib/python3.9/site-packages/django/db/models/query.py"", line 512, in create
    obj = self.model(**kwargs)
  File ""/home/.../venv/lib/python3.9/site-packages/django/db/models/base.py"", line 541, in __init__
    _setattr(self, field.name, rel_obj)
  File ""/home/.../venv/lib/python3.9/site-packages/django/db/models/fields/related_descriptors.py"", line 235, in __set__
    raise ValueError(
ValueError: Cannot assign ""<Foo: Foo object (...)>"": ""Bar.foo"" must be a ""Foo"" instance.
}}}

This error is coming from a `RunPython()` function. It's using a model from `apps.get_model()`, querying a model instance, and then using that instance in a ForeignKey field. I assume the error is because the type from `apps.get_model()` isn't the same as the actual model class.

Essentially this is what it's doing:

{{{
def custom_migration_func(apps, schema_editor):
    Foo = apps.get_model(""foo"", ""Foo"")
    Bar = apps.get_model(""bar"", ""Bar"")

    for foo in Foo.objects.all():
        Bar.objects.create(foo=foo)  # breaks here
}}}

I was able to workaround this by setting the ID directly:

{{{
Bar.objects.create(foo_id=foo.pk)
}}}

If adding support for this isn't feasible, the documentation should at least be updated to address this. I wasn't able to find any information regarding this in the docs."	Bug	closed	Migrations	4.0	Normal	needsinfo			Unreviewed	0	0	0	0	0	0