Make some mixin methods generic (#131)

Author: henribru

rest_framework-stubs/mixins.pyi

@@ -1,13 +1,17 @@
-from typing import Any, Dict
+from typing import Any, Dict, TypeVar
 
 from django.db.models import Model
+
+from rest_framework.generics import UsesQuerySet
 from rest_framework.request import Request
 from rest_framework.response import Response
 from rest_framework.serializers import BaseSerializer
 
+_MT = TypeVar("_MT", bound=Model)
+
 class CreateModelMixin:
     def create(self, request: Request, *args: Any, **kwargs: Any) -> Response: ...
-    def perform_create(self, serializer: BaseSerializer) -> None: ...
+    def perform_create(self: UsesQuerySet[_MT], serializer: BaseSerializer[_MT]) -> None: ...
     def get_success_headers(self, data: Any) -> Dict[str, str]: ...
 
 class ListModelMixin:
@@ -18,9 +22,9 @@ class RetrieveModelMixin:
 
 class UpdateModelMixin:
     def update(self, request: Request, *args: Any, **kwargs: Any) -> Response: ...
-    def perform_update(self, serializer: BaseSerializer) -> None: ...
+    def perform_update(self: UsesQuerySet[_MT], serializer: BaseSerializer[_MT]) -> None: ...
     def partial_update(self, request: Request, *args: Any, **kwargs: Any) -> Response: ...
 
 class DestroyModelMixin:
     def destroy(self, request: Request, *args: Any, **kwargs: Any) -> Response: ...
-    def perform_destroy(self, instance: Model) -> None: ...
+    def perform_destroy(self: UsesQuerySet[_MT], instance: _MT) -> None: ...

tests/typecheck/test_mixins.yml

@@ -0,0 +1,38 @@
+- case: test_create
+  main: |
+    from rest_framework.mixins import CreateModelMixin
+    from rest_framework.generics import GenericAPIView
+    from rest_framework.serializers import BaseSerializer, ModelSerializer
+    from django.db.models import Model
+
+    class MyModel(Model):
+        pass
+
+    class MyView(GenericAPIView, CreateModelMixin):
+        def perform_create(self, serializer: BaseSerializer[MyModel]) -> None: ...
+
+- case: test_perform_update
+  main: |
+    from rest_framework.mixins import UpdateModelMixin
+    from rest_framework.generics import GenericAPIView
+    from rest_framework.serializers import BaseSerializer
+    from django.db.models import Model
+
+    class MyModel(Model):
+        pass
+
+    class MyView(GenericAPIView, UpdateModelMixin):
+        def perform_update(self, serializer: BaseSerializer[MyModel]) -> None: ...
+
+- case: test_perform_destroy
+  main: |
+    from rest_framework.mixins import DestroyModelMixin
+    from rest_framework.generics import GenericAPIView
+    from rest_framework.serializers import BaseSerializer
+    from django.db.models import Model
+
+    class MyModel(Model):
+        pass
+
+    class MyView(GenericAPIView, DestroyModelMixin):
+        def perform_destroy(self, instance: MyModel) -> None: ...

tests/typecheck/test_views.yml

@@ -6,3 +6,16 @@
         def filter_queryset(self, queryset):
             reveal_type(self.request)  # N: Revealed type is 'rest_framework.request.Request'
             return queryset
+
+- case: test_destroy_api_view
+  main: |
+    from rest_framework import generics
+    from django.db.models import Model
+
+    class MyModel(Model):
+        pass
+
+    class MyView(generics.DestroyAPIView):
+        queryset = MyModel.objects.all()
+
+        def perform_destroy(self, instance: MyModel) -> None: ...