mypy and type checking

Using Django Getting Started
1

I’m trying to enable type hints for my Django REST project. I installed django-stubs and djangorestframework-stubs and I have the following mypy.ini file:

[mypy]
plugins =
    mypy_django_plugin.main
    mypy_drf_plugin.main

[mypy.plugins.django-stubs]
django_settings_module = "core.settings.base"

Some of the type hints do work; for example, if I have a variable inside of a method whose type is a model class, I get hints when I try to access a field or method defined on it.

However, if I try to access a Django-specific field on the model, for example a reverse relation, that does not typecheck and gives me an error. Moreover, if I try to access fields on a related model of my model variable, the related object has type Any

For example, with these two models:

class User(models.Model):
    name = models.TextField()
    role = models.ForeignKey(Role) # definition of Role model not relevant

class Badge(models.Model):
    user = models.ForeignKey(User, related_name="badges")

then this will happen:

u: User = get_user()
print(u.name) # correctly hinted and typechecks
print(u.badges.all()) # type error
print(u.role.pk) # no hint on role.pk, role is Any

How do I get my project to correclty type check all the Django-specific features such as foreign key fields, querysets, and reverse relationships?

2

There’s a million threads about this and no solution?

Nobody at DJANGO cares enough to support MYPY the industry standard for python?

Amazing …

4

Skipping analyzing “django.core.management”: module is installed, but missing library stubs or py.typed marker [import-untyped]
Skipping analyzing “django.core.wsgi”: module is installed, but missing library stubs or py.typed marker [import-untyped]
Skipping analyzing “django.urls”: module is installed, but missing library stubs or py.typed marker [import-untyped]
Skipping analyzing “django.conf”: module is installed, but missing library stubs or py.typed marker [import-untyped]
Skipping analyzing “django.conf.urls.static”: module is installed, but missing library stubs or py.typed marker
Skipping analyzing “django.core.asgi”: module is installed, but missing library stubs or py.typed marker [import-untyped]

and many, many more.

1 Like
5

I think you may have a misunderstanding about how the Django project is organized.

There is no “at Django”. Django is not a company or a product from a company. It is a completely community-driven project. The features that people choose to work on are what get added. It’s not directed by any one individual or group.

Additionally, there has been some work in this direction - see GitHub - typeddjango/django-stubs: PEP-484 stubs for Django

In other words, if it is so important to you that Mypy be supported, then I encourage you to work on it! That is how Django moves forward.

1 Like
6

yes, this is only important to me lmaoooo

why does mypy exist then huh?

7

You have misinterpreted what I have said. Clearly I have acknowledged that there is interest by identifying the project that is working on it.

What I said was that people who are interested in it need to step up and work on it, because that’s the only way it’s going to get added.

It doesn’t help to sit back and say “Someone needs to work on this”. I’m pointing out that in Django, you are one of the “Someone”. I’m sure the django-stubs project would greatly appreciate your contributions.

Because a “Someone” thought it would be worthwhile and made the decision to work on it. Again, that’s how progress is made. Those individuals didn’t just write posts saying “Someone should implement this.” They’ve gone ahead and done it.

<opinion>
(Personally, I don’t care if it ever gets added. I can see value to adding it to Django core, but I don’t have any desire to implement it in any code that I write.)
</opinion>