Allow form.save() in CreateView / UpdateView (#374)

django-stubs/views/generic/edit.pyi

@@ -1,28 +1,35 @@
 from typing import Any, Callable, Dict, Optional, Sequence, Type, Union
 
 from django.forms.forms import BaseForm
+from django.forms.models import BaseModelForm
 from django.views.generic.base import ContextMixin, TemplateResponseMixin, View
 from django.views.generic.detail import BaseDetailView, SingleObjectMixin, SingleObjectTemplateResponseMixin
 from typing_extensions import Literal
 
 from django.http import HttpRequest, HttpResponse
 
-class FormMixin(ContextMixin):
+class AbstractFormMixin(ContextMixin):
     initial: Dict[str, Any] = ...
     form_class: Optional[Type[BaseForm]] = ...
     success_url: Optional[Union[str, Callable[..., Any]]] = ...
     prefix: Optional[str] = ...
     def get_initial(self) -> Dict[str, Any]: ...
     def get_prefix(self) -> Optional[str]: ...
-    def get_form_class(self) -> Type[BaseForm]: ...
-    def get_form(self, form_class: Optional[Type[BaseForm]] = ...) -> BaseForm: ...
     def get_form_kwargs(self) -> Dict[str, Any]: ...
     def get_success_url(self) -> str: ...
+
+class FormMixin(AbstractFormMixin):
+    def get_form_class(self) -> Type[BaseForm]: ...
+    def get_form(self, form_class: Optional[Type[BaseForm]] = ...) -> BaseForm: ...
     def form_valid(self, form: BaseForm) -> HttpResponse: ...
     def form_invalid(self, form: BaseForm) -> HttpResponse: ...
 
-class ModelFormMixin(FormMixin, SingleObjectMixin):
+class ModelFormMixin(AbstractFormMixin, SingleObjectMixin):
     fields: Optional[Union[Sequence[str], Literal["__all__"]]] = ...
+    def get_form_class(self) -> Type[BaseModelForm]: ...
+    def get_form(self, form_class: Optional[Type[BaseModelForm]] = ...) -> BaseModelForm: ...
+    def form_valid(self, form: BaseModelForm) -> HttpResponse: ...
+    def form_invalid(self, form: BaseModelForm) -> HttpResponse: ...
 
 class ProcessFormView(View):
     def get(self, request: HttpRequest, *args: str, **kwargs: Any) -> HttpResponse: ...

test-data/typecheck/test_forms.yml

@@ -46,6 +46,18 @@
                 reveal_type(self.get_form(form_class))  # N: Revealed type is 'main.MyForm'
                 reveal_type(self.get_form(MyForm2))  # N: Revealed type is 'main.MyForm2'
 
+-   case: updateview_form_valid_has_form_save
+    main: |
+        from django import forms
+        from django.views.generic.edit import UpdateView
+
+        class MyForm(forms.ModelForm):
+            pass
+        class MyView(UpdateView):
+            form_class = MyForm
+            def form_valid(self, form: forms.BaseModelForm):
+                reveal_type(form.save)  # N: Revealed type is 'def (commit: builtins.bool =) -> Any'
+
 -   case: successmessagemixin_compatible_with_formmixin
     main: |
         from django.views.generic.edit import FormMixin