"Type[Model]" has no attribute "objects" (again?)

[kam1sh]

Hello. I tried to use your package yesterday and I like it, although I've encountered one issue, when the django model I was accessing had no attribute 'objects', according to mypy. So it's like #16:

...
anchor/users/forms.py:26: error: "Type[Model]" has no attribute "objects"
anchor/users/views.py:38: error: "Type[Model]" has no attribute "objects"
...

The repo where I found that is https://github.com/kam1sh/anchor.

Also, I looked at django-stubs source code, and the class had no 'objects' field at all. Is it intended?

https://github.com/mkurnikov/django-stubs/blob/0e60b70ae4f521e3a527997d6b79e461d9245dfa/django-stubs/db/models/base.pyi#L9-L16

[mkurnikov]

Try to enable plugin in mypy.ini via plugins = mypy_django_plugin.main. Let me know if it helped.

[kam1sh]

I've already enabled that, but did not commited yet =)

Also, without plugin there is no errors at all, but they showed up when I installed django-stubs (and typing with typing-extensions as its dependencies):

igor@juno [19:29:48] ~/p/ciconia> mypy anchor
<no output>
igor@juno [19:31:41] ~/p/ciconia> poetry add --dev django-stubs
Using version ^0.12.1 for django-stubs

Updating dependencies
Resolving dependencies... (0.7s)


Package operations: 3 installs, 0 updates, 0 removals

Writing lock file

  - Installing typing (3.6.6)
  - Installing typing-extensions (3.7.2)
  - Installing django-stubs (0.12.1)

igor@juno [19:26:25] ~/p/ciconia> vim setup.cfg # enabled django-stubs plugin
igor@juno [19:32:04] ~/p/anchor> mypy anchor
anchor/users/forms.py:9: error: Name 'forms.UserChangeForm.Meta' is not defined
anchor/users/forms.py:19: error: Name 'forms.UserCreationForm.Meta' is not defined
anchor/users/forms.py:26: error: "Type[Model]" has no attribute "objects"
anchor/users/views.py:38: error: "Type[Model]" has no attribute "objects"
anchor/pypi/models.py:16: error: Module 'django.shortcuts' has no attribute 'reverse'
anchor/pypi/services.py:8: note: unused 'type: ignore' comment

[mkurnikov]

Yeah, this is Form related stuff, I don't think I tested it much. On internal codebases we only used APIs with DRF.
Probably a valid bug then.

[kam1sh]

I don't ise forms a lot too, those were created by cookiecutter template automatically.

I'll try to fix that and file a pull request tomorrow.

[bluetech]

The errors you describe in the issue are due to the typing of get_user_model():

def get_user_model() -> Type[Model]

Indeed given just a general Model you can't know that there is an objects, and it will be useless anyway.

You have two avenues to improve this as far as I can see:

1. Change your code to not use get_user_model but use a concrete model instead. This is only possible if you don't need to support any arbitrarily-configured user model. In your case, seems like you can just import from .models import User instead of User = get_user_model() and that will fix the problem.

2. Improve the typing of get_user_model(). I didn't investigate this, but there might be some base class or protocol that every custom user model needs to have. I don't know if it requires objects though. Second alternative is to somehow make get_user_model() return the model that is actually configured in the AUTH_USER_MODEL setting. That would be best, but I don't know if it's possible, maybe @mkurnikov can say.

[kam1sh]

I dived in the Django sources, and AbstractUser has objects class variable (contrib/auth/models.py)

So then maybe signature should be like get_user_model() -> Type[AbstractUser] and AbstractUser have a objects = ClassVar[UserManager]?

P.S.: I found yours mypy hook that checks AUTH_USER_MODEL and extracts its value. Cool thing, didn't know about that.

[ivanrvpereira]

I use an abstract BaseModel, and for models using this BaseModel class mypy gives the "Type[Model]" has no attribute "objects"

[mkurnikov]

If BaseModel does not depend on django.db.models.Model, it won't work.

[mkurnikov]

If issue is indeed with get_user_model() typing, it should be fixed in #109

[ivanrvpereira]

BaseModel depends on django.db.models.Model

[mkurnikov]

Wait for #109, I've added default objects to models.Model there and fixed a bunch of related bugs. I would be great if you'd test it now, so that I could fix your case before merging.

UPD. Problem here, I think, is because BaseModel does not have objects itself, because it's abstract. It's just a guess though. Try new PR=)

[ivanrvpereira]

Installing #109 version fixes the reported error, but another one came up. I don't know if it is related with the version on #109
Error importing plugin 'mypy_drf_plugin.main'

[mkurnikov]

DRF plugin is not compatible to new branch yet, sorry.

Will be at the end of the week.