TypeError: can't adapt type '_FakeSqlVal'

[jordanvs]

I'm on Django 3.2 / Postgres. When I go to save a model in Django Admin that is using a Multiselect field (note the model is also polymorphic using django-polymorphic), this error occurs. I can't trace it back to anything. Haven't been able to look through the library code yet.

This occured for me on the latest bump to 0.1.13 version. For now I have to downgrade back to 0.1.12 which solves the issue.

[isacmms]

This started happening with me recently. pip-compile updated from version 0.1.12 to 0.1.13.

I have a model A which is a configuration to generate new records of model B. The model A is created and have no problems saving this multiselectfield. There is another routine that copies this field from model A on a new instance of model B and when saving B is when the error occurs.

If model clean field is running it throws TypeError: '>' not supported between instances of 'int' and 'NoneType' when running MaxValueValidator or MaxLengthValidator. If not, it throws TypeError: can't adapt type '_FakeSqlVal'.
The column on database of model B is correct, but the model field has all choices loaded as None on application and end up passing a list of None to model A causing these problems on save.