django-oscar-stubs 4.1.0b2

PEP 561 type stubs for django-oscar

django-oscar-stubs

PEP 561 type stubs for django-oscar.

Includes a custom mypy plugin that resolves the return types of oscar's dynamic class loading functions (get_model, get_class, get_classes) to the actual concrete types, including support for forked apps.

Installation

pip install django-oscar-stubs

Configuration

Add mypy_oscar_plugin to your mypy plugins, alongside mypy_django_plugin.main from django-stubs:

# mypy.ini
[mypy]
plugins =
    mypy_django_plugin.main,
    mypy_oscar_plugin

[mypy.plugins.django-stubs]
django_settings_module = myproject.settings

The oscar plugin reads django_settings_module from the django-stubs config section (or the DJANGO_SETTINGS_MODULE environment variable) to detect forked apps. Plugin ordering does not matter, but both plugins must be listed.

What it does

Type-safe dynamic loading

Oscar uses get_model and get_class to dynamically load models and classes. Without the plugin, these return untyped type objects. With the plugin, mypy resolves them to the actual types:

from oscar.core.loading import get_model, get_class, get_classes

# Without plugin: type[Model]
# With plugin:    type[oscar.apps.catalogue.models.Product]
Product = get_model("catalogue", "Product")

# Without plugin: type
# With plugin:    type[oscar.apps.address.forms.UserAddressForm]
UserAddressForm = get_class("address.forms", "UserAddressForm")

# Without plugin: list[type]
# With plugin:    tuple[type[BasketLineForm], type[SavedLineForm]]
BasketLineForm, SavedLineForm = get_classes(
    "basket.forms", ["BasketLineForm", "SavedLineForm"]
)

Forked app support

When your project forks an oscar app, the plugin detects this from INSTALLED_APPS and resolves to your forked types instead of oscar's defaults:

# settings.py
INSTALLED_APPS = [
    ...
    "myproject.catalogue.apps.CatalogueConfig",  # forked from oscar
    "oscar.apps.basket.apps.BasketConfig",        # not forked
    ...
]

# myproject/catalogue/models.py
from oscar.apps.catalogue.abstract_models import AbstractProduct

class Product(AbstractProduct):
    custom_field = models.CharField(max_length=100)

# Resolves to type[myproject.catalogue.models.Product] (with custom_field!)
Product = get_model("catalogue", "Product")
Product.objects.filter(custom_field="foo")  # type-safe

The plugin falls back to oscar's default types for any app that hasn't been forked, or when literal string arguments aren't used.