This package contains type stubs and a custom mypy plugin to provide more precise static types and type inference for Django framework. Django uses some Python "magic" that makes having precise types for some code patterns problematic. This is why we need this project. The final goal is to be able to get precise types for most common patterns.
pip install 'django-stubs[compatible-mypy]'
To make mypy aware of the plugin, you need to add
[mypy]
plugins =
mypy_django_plugin.main
[mypy.plugins.django-stubs]
django_settings_module = "myproject.settings"
in your mypy.ini
or setup.cfg
file.
pyproject.toml configurations are also supported:
[tool.mypy]
plugins = ["mypy_django_plugin.main"]
[tool.django-stubs]
django_settings_module = "myproject.settings"
Two things happening here:
- We need to explicitly list our plugin to be loaded by
mypy
- You can either specify
django_settings_module
as seen above, or letdjango_stubs
use theDJANGO_SETTINGS_MODULE
variable from your environment.
This fully working typed boilerplate can serve you as an example.
We rely on different django
and mypy
versions:
django-stubs | Mypy version | Django version | Django partial support | Python version |
---|---|---|---|---|
5.0.4 | 1.11.x | 5.0 | 4.2 | 3.8 - 3.12 |
5.0.3 | 1.11.x | 5.0 | 4.2 | 3.8 - 3.12 |
5.0.2 | 1.10.x | 5.0 | 4.2 | 3.8 - 3.12 |
5.0.1 | 1.10.x | 5.0 | 4.2 | 3.8 - 3.12 |
5.0.0 | 1.10.x | 5.0 | 4.2, 4.1 | 3.8 - 3.12 |
4.2.7 | 1.7.x | 4.2 | 4.1, 3.2 | 3.8 - 3.12 |
4.2.6 | 1.6.x | 4.2 | 4.1, 3.2 | 3.8 - 3.12 |
4.2.5 | 1.6.x | 4.2 | 4.1, 3.2 | 3.8 - 3.12 |
4.2.4 | 1.5.x | 4.2 | 4.1, 3.2 | 3.8 - 3.11 |
4.2.3 | 1.4.x | 4.2 | 4.1, 3.2 | 3.8 - 3.11 |
4.2.2 | 1.4.x | 4.2 | 4.1, 3.2 | 3.8 - 3.11 |
4.2.1 | 1.3.x | 4.2 | 4.1, 3.2 | 3.8 - 3.11 |
4.2.0 | 1.2.x | 4.2 | 4.1, 4.0, 3.2 | 3.7 - 3.11 |
1.16.0 | 1.1.x | 4.1 | 4.0, 3.2 | 3.7 - 3.11 |
1.15.0 | 1.0.x | 4.1 | 4.0, 3.2 | 3.7 - 3.11 |
1.14.0 | 0.990+ | 4.1 | 4.0, 3.2 | 3.7 - 3.11 |
By inheriting from the TypedModelMeta
class, you can ensure you're using correct types for
attributes:
from django.db import models
from django_stubs_ext.db.models import TypedModelMeta
class MyModel(models.Model):
example = models.CharField(max_length=100)
class Meta(TypedModelMeta):
ordering = ["example"]
constraints = [
models.UniqueConstraint(fields=["example"], name="unique_example"),
]
django_stubs_ext.db.router.TypedDatabaseRouter
can be used as base when implementing custom database routers.
django-stubs has a few settings, which you can list in:
pyproject.toml
, under the table[tool.django-stubs]
mypy.ini
under the table[mypy.plugins.django-stubs]
The supported settings are:
-
django_settings_module
, a string, default toos.getenv(DJANGO_SETTINGS_MODULE)
.Specify the import path of your settings module, the same as Django’s
DJANGO_SETTINGS_MODULE
environment variable. -
strict_settings
, a boolean, defaulttrue
.Set to
false
if using dynamic settings, as described below.
No, it is not. We are independent from Django at the moment. There's a proposal to merge our project into the Django itself. You can show your support by liking the PR.
Yes, it is! This project does not affect your runtime at all.
It only affects mypy
type checking process.
But, it does not make any sense to use this project without mypy
.
The current implementation uses Django's runtime to extract information about models, so it might crash if your installed apps or models.py
are broken.
In other words, if your manage.py runserver
crashes, mypy will crash too.
You can also run mypy
with --tb
option to get extra information about the error.
You can get a TypeError: 'type' object is not subscriptable
when you will try to use QuerySet[MyModel]
, Manager[MyModel]
or some other Django-based Generic types.
This happens because these Django classes do not support __class_getitem__
magic method in runtime.
-
You can go with our
django_stubs_ext
helper, that patches all the types we use as Generic in django.Install it:
pip install django-stubs-ext # as a production dependency
And then place in your top-level settings:
import django_stubs_ext django_stubs_ext.monkeypatch()
You can add extra types to patch with
django_stubs_ext.monkeypatch(extra_classes=[YourDesiredType])
-
You can use strings instead:
'QuerySet[MyModel]'
and'Manager[MyModel]'
, this way it will work as a type formypy
and as a regularstr
in runtime.
Django's built in HttpRequest
has the attribute user
that resolves to the type
Union[User, AnonymousUser]
where User
is the user model specified by the AUTH_USER_MODEL
setting.
If you want a HttpRequest
that you can type-annotate with where you know that the user is authenticated you can subclass the normal HttpRequest
class like so:
from django.http import HttpRequest
from my_user_app.models import MyUser
class AuthenticatedHttpRequest(HttpRequest):
user: MyUser
And then use AuthenticatedHttpRequest
instead of the standard HttpRequest
for when you know that the user is authenticated. For example in views using the @login_required
decorator.
If you declare your custom managers without generics and override built-in methods you might see an error message about incompatible error messages, something like this:
from django.db import models
class MyManager(model.Manager):
def create(self, **kwargs) -> "MyModel":
pass
will cause this error message:
error: Return type "MyModel" of "create" incompatible with return type "_T" in supertype "BaseManager"
This is happening because the Manager
class is generic, but without
specifying generics the built-in manager methods are expected to return the
generic type of the base manager, which is any model. To fix this issue you
should declare your manager with your model as the type variable:
class MyManager(models.Manager["MyModel"]):
...
Django-stubs provides a special type, django_stubs_ext.WithAnnotations[Model, <Annotations>]
, which indicates that
the Model
has been annotated, meaning it requires extra attributes on the model instance.
You should provide a TypedDict
of these attributes, e.g. WithAnnotations[MyModel, MyTypedDict]
, to specify which
annotated attributes are present.
Currently, the mypy plugin can recognize that specific names were passed to QuerySet.annotate
and
include them in the type, but does not record the types of these attributes.
The knowledge of the specific annotated fields is not yet used in creating more specific types for QuerySet
's
values
, values_list
, or filter
methods, however knowledge that the model was annotated is used to create a
broader type result type for values
/values_list
, and to allow filter
ing on any field.
from typing import TypedDict
from django_stubs_ext import WithAnnotations
from django.db import models
from django.db.models.expressions import Value
class MyModel(models.Model):
username = models.CharField(max_length=100)
class MyTypedDict(TypedDict):
foo: str
def func(m: WithAnnotations[MyModel, MyTypedDict]) -> str:
print(m.bar) # Error, since field "bar" is not in MyModel or MyTypedDict.
return m.foo # OK, since we said field "foo" was allowed
func(MyModel.objects.annotate(foo=Value("")).get(id=1)) # OK
func(MyModel.objects.annotate(bar=Value("")).get(id=1)) # Error
The lazy translation functions of Django (such as gettext_lazy
) return a Promise
instead of str
. These two types cannot be used interchangeably. The return type of these functions was therefore changed to reflect that.
If you encounter this error in your own code, you can either cast the Promise
to str
(causing the translation to be evaluated), or use the StrPromise
or StrOrPromise
types from django-stubs-ext
in type hints. Which solution to choose depends depends on the particular case. See working with lazy translation objects in the Django documentation for more information.
If this is reported on Django code, please report an issue or open a pull request to fix the type hints.
Using something like django-split-settings
or django-configurations
will make it hard for mypy to infer your settings.
This might also be the case when using something like:
try:
from .local_settings import *
except Exception:
pass
So, mypy would not like this code:
from django.conf import settings
settings.CUSTOM_VALUE # E: 'Settings' object has no attribute 'CUSTOM_VALUE'
To handle this corner case we have a special setting strict_settings
(True
by default),
you can switch it to False
to always return Any
and not raise any errors if runtime settings module has the given value,
for example pyproject.toml
:
[tool.django-stubs]
strict_settings = false
or mypy.ini
:
[mypy.plugins.django-stubs]
strict_settings = false
And then:
# Works:
reveal_type(settings.EXISTS_AT_RUNTIME) # N: Any
# Errors:
reveal_type(settings.MISSING) # E: 'Settings' object has no attribute 'MISSING'
awesome-python-typing
- Awesome list of all typing-related things in Python.djangorestframework-stubs
- Stubs for Django REST Framework.pytest-mypy-plugins
-pytest
plugin that we use for testingmypy
stubs and plugins.wemake-django-template
- Create new typed Django projects in seconds.
We have Gitter here: https://gitter.im/mypy-django/Lobby If you think you have more generic typing issue, please refer to https://github.com/python/mypy and their Gitter.
This project is open source and community driven. As such we encourage contributions big and small. You can contribute by doing any of the following:
- Contribute code (e.g. improve stubs, add plugin capabilities, write tests etc) - to do so please follow the contribution guide.
- Assist in code reviews and discussions in issues.
- Identify bugs and issues and report these
- Ask and answer questions on StackOverflow
You can always also reach out in gitter to discuss your contributions!