fix(django-import-export): ForeignKeyWidget.__init__ argument types

[VictorColomb]

Issue statement

In the stubs for django-import-export, the model argument of the widgets.ForeignKeyWidget.__init__ method is incorrectly typed as _ModelT, which corresponds to a Django model instance, whereas the method actually expects the model itself, i.e. type[_ModelT].

MRE

from django.db.models import CASCADE, CharField, ForeignKey, Model
from import_export.resources import ModelResource
from import_export.widgets import ForeignKeyWidget


class RelatedModel(Model):
    label = CharField()


class MyModel(Model):
    related = ForeignKey(RelatedModel, on_delete=CASCADE)


class MyModelResource(ModelResource[MyModel]):
    related = ForeignKeyWidget(RelatedModel, field="label")

    class Meta:
        model = MyModel
        fields = ("related",)

The above code corresponds to the django-import-export documentation ¹, and actually works. Yet:

$ mypy .
mre.py:15: error: Value of type variable "_ModelT" of "ForeignKeyWidget" cannot be "type[RelatedModel]"  [type-var]
Found 1 errors in 1 file (checked 1 source file)

Footnotes

1. https://django-import-export.readthedocs.io/en/latest/api_widgets.html#import_export.widgets.ForeignKeyWidget ↩

[github-actions]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉