get_user_model_hook raises LookupError without auth app

[meshy]

Bug report

What's wrong

Djangn-stubs causes mypy to crashe with LookupError when:

• django.contrib.auth is not in INSTALLED_APPS,
• any imported code references get_user_model().

This happened to me because I'm importing SettingsWrapper from pytest_django.fixtures. Mypy then wants a type for get_user_model because pytest_django's django_user_model fixture imports and returns get_user_model() in that module.

When get_user_model_hook is called, but the auth app isn't installed, Django raises a LookupError. I must admit, I have no idea what it should return.

This is similar to #318.

Traceback:

Traceback (most recent call last):
  File "mypy/checkexpr.py", line 4813, in accept
  File "mypy/checkexpr.py", line 425, in visit_call_expr
  File "mypy/checkexpr.py", line 545, in visit_call_expr_inner
  File "mypy/checkexpr.py", line 1197, in check_call_expr_with_callee_type
  File "mypy/checkexpr.py", line 1280, in check_call
  File "mypy/checkexpr.py", line 1490, in check_callable_call
  File "mypy/checkexpr.py", line 1020, in apply_function_plugin
  File "/.../python3.10/site-packages/mypy_django_plugin/transformers/settings.py", line 13, in get_user_model_hook
    model_cls = django_context.apps_registry.get_model(auth_user_model)
  File "/.../python3.10/site-packages/django/apps/registry.py", line 206, in get_model
    app_config = self.get_app_config(app_label)
  File "/.../python3.10/site-packages/django/apps/registry.py", line 163, in get_app_config
    raise LookupError(message)
LookupError: No installed app with label 'auth'.

/.../python3.10/site-packages/pytest_django/fixtures.py:397: : note: use --pdb to drop into pdb

How it should work

get_user_model_hook should not raise an error when there is no auth app.

System information

• OS: Ubuntu 22.04.2 LTS
• python version: 3.10.6
• django version: 3.1
• mypy version: 1.0.1
• django-stubs version: 1.15.0
• django-stubs-ext version: 0.7.0

[BranislavBajuzik]

I had this exact problem. The Mypy code that throws this uses your settings.AUTH_USER_MODEL. My problem was that I pointed to empty (the __init__.py 😅) settings so the default value of auth.User was used instead of what I put in there.