Upgrade mypy & django-stubs

This was pretty simply generated:

    poetry update mypy django-stubs

After performing the update, 7 errors must be fixed in 3 files!

ws/forms.py

@@ -432,7 +432,9 @@ def clean_winter_terrain_level(self) -> str | None:
         program = self.cleaned_data.get("program")
         if program and not enums.Program(program).winter_rules_apply():
             return None
-        return self.cleaned_data.get("winter_terrain_level", "")
+        level = self.cleaned_data.get("winter_terrain_level", "")
+        assert isinstance(level, str)
+        return level
 
     def _init_wimp(self):
         """Configure the WIMP widget, load saved participant if applicable."""

ws/models.py

@@ -10,7 +10,7 @@
 from bs4 import BeautifulSoup
 from django.conf import settings
 from django.contrib.auth.models import AnonymousUser, User
-from django.contrib.contenttypes.models import ContentType, ContentTypeManager
+from django.contrib.contenttypes.models import ContentType
 from django.contrib.postgres.indexes import GistIndex
 from django.contrib.postgres.search import SearchQuery, SearchRank, SearchVector
 from django.core.exceptions import ValidationError
@@ -53,8 +53,9 @@ def delete(self, *args, **kwargs):  # pylint: disable=signature-differs
 
     @classmethod
     def load(cls) -> Self:
-        obj, _created = cls.objects.get_or_create(pk=1)
-        return obj
+        manager: QuerySet = cls.objects  # type:ignore[attr-defined]
+        obj, _created = manager.get_or_create(pk=1)
+        return cast(Self, obj)
 
 
 class Car(models.Model):
@@ -118,7 +119,7 @@ class Discount(models.Model):
     """Discount at another company available to MITOC members."""
 
     administrators = models.ManyToManyField(
-        "Participant",
+        "ws.Participant",
         blank=True,
         help_text="Persons selected to administer this discount",
         related_name="discounts_administered",
@@ -1857,13 +1858,21 @@ def activity(self) -> str:
         If any class wants to break the naming convention, they should
         set db_name to be the activity without underscores.
         """
-        content_type = cast(ContentTypeManager, ContentType.objects).get_for_model(self)
+        content_type = ContentType.objects.get_for_model(self)
         model_name: str = content_type.model
         activity = model_name[: model_name.rfind("leaderapplication")]
         return "winter_school" if (activity == "winterschool") else activity
 
     @staticmethod
-    def model_from_activity(activity: enums.Activity) -> type["LeaderApplication"]:
+    def model_from_activity(
+        activity: enums.Activity,
+    ) -> (
+        # Technically, `type[LeaderApplication]` would work too.
+        # However, being specific about supported applications helps mypy.
+        type["ClimbingLeaderApplication"]
+        | type["HikingLeaderApplication"]
+        | type["WinterSchoolLeaderApplication"]
+    ):
         """Get the specific inheriting child from the activity.
 
         Inverse of activity().
@@ -1879,7 +1888,14 @@ def model_from_activity(activity: enums.Activity) -> type["LeaderApplication"]:
         model_class = content_type.model_class()
         if model_class is None:
             raise NoApplicationDefinedError(f"No application for {activity.label}")
-        assert issubclass(model_class, LeaderApplication)
+        assert issubclass(
+            model_class,
+            (
+                ClimbingLeaderApplication
+                | HikingLeaderApplication
+                | WinterSchoolLeaderApplication
+            ),
+        )
         return model_class
 
 

ws/utils/ratings.py

@@ -46,7 +46,13 @@ def activity_chairs(self) -> QuerySet[User]:
 
     # The model is meant to be a class attribute of SingleObjectMixin
     @property
-    def model(self) -> type[models.LeaderApplication]:
+    def model(
+        self,
+    ) -> (
+        type[models.ClimbingLeaderApplication]
+        | type[models.HikingLeaderApplication]
+        | type[models.WinterSchoolLeaderApplication]
+    ):
         """Return the application model for this activity type.
 
         The model will be None if no application exists for the activity.