Does not work with django-auto-prefetch models and fields

[yatharth]

Bug report

What's wrong

django-stubs fails to work with models using django-auto-prefetch.

If I have a class like this:

import 

class Bar(auto_prefetch.Model):
   bar = CharField(max_length=10)

class Foo(auto_prefetch.Model):
    foo = auto_prefetch.ForeignKey(
        Bar, on_delete=models.PROTECT
    )

and then I try to typecheck this code

def hello(foo: Foo):
    print(foo.bar)

I get errors like this:

[...].py:[...]: error: "Model" has no attribute "bar"

How is that should be

Whatever django-stubs is doing to make regular models and ForeignKeys work should also work with models that are inheriting from auto_prefetch.Model.

System information

• OS: macOS 13.1
• python version: 3.11
• django version: 3.2.18
• mypy version: 0.961
• django-stubs version: 1.12.0
• django-stubs-ext version: 0.5.0

[sobolevn]

Just a tip, that you can lie about the base class with if TYPE_CHECKING: _base: TypeAlias = Model; else: _base: TypeAlias = auto_prefetch.Model

[flaeppe]

I'm not sure this is an issue with django-stubs? Since django-auto-prefetch doesn't seem to include package data for py.typed, essentially making it an untyped package?

Unless I'm missing something

[flaeppe]

I've also tried inherited models.Model in the past, which has gotten stuff working for me:

class Foo(auto_prefetch.Model, models.Model):
    foo = auto_prefetch.ForeignKey(
        Bar, on_delete=models.PROTECT
    )

[intgr]

Actually it does have py.typed, courtesy of our own adamchainz 😄

https://github.com/tolomea/django-auto-prefetch/tree/main/src/auto_prefetch

Maybe our detection of Model classes doesn't consider subclasses of Django's Model?

[flaeppe]

It has a py.typed. But it's not included in package_data in setup.cfg (I haven't inspected a pypi installation though, just browsing around and comparing config to other packages)

[flaeppe]

I just had a look at a fresh pypi installation though, it looks fine. So I was wrong 🙂

 ➤ pip show -f django-auto-prefetch
Name: django-auto-prefetch
Version: 1.5.1
Summary: Automatically prefetch foreign key values as needed.
Home-page: https://github.com/tolomea/django-auto-prefetch
Author: Gordon Wrigley
Author-email: gordon.wrigley@gmail.com
License: BSD-3-Clause
Location: ./.venv/lib/python3.10/site-packages
Requires: Django
Required-by:
Files:
  auto_prefetch/__init__.py
  auto_prefetch/__pycache__/__init__.cpython-310.pyc
  auto_prefetch/py.typed
  django_auto_prefetch-1.5.1.dist-info/INSTALLER
  django_auto_prefetch-1.5.1.dist-info/LICENSE
  django_auto_prefetch-1.5.1.dist-info/METADATA
  django_auto_prefetch-1.5.1.dist-info/RECORD
  django_auto_prefetch-1.5.1.dist-info/REQUESTED
  django_auto_prefetch-1.5.1.dist-info/WHEEL
  django_auto_prefetch-1.5.1.dist-info/top_level.txt

[adamchainz]

Yes, the package has basic typing. I haven't sorted out making it strict-mode-compatible yet (adamchainz/django-auto-prefetch#217) so perhaps some missing generic parameters would help there. If you have time to try out on that PR, it would be useful.