Improves edit.py and its forms (#648)

* Improves edit.py and its forms

* Adds tests

dev-requirements.txt

@@ -1,10 +1,11 @@
 wheel
+black==21.6b0
 requests==2.24.0
 coreapi==2.3.3
 gitpython==3.1.9
 pre-commit==2.7.1
 pytest==6.1.1
-pytest-mypy-plugins==1.6.1
+pytest-mypy-plugins==1.7.0
 psycopg2-binary
 types-toml==0.1.1
 -e ./django_stubs_ext

django-stubs/contrib/postgres/indexes.pyi

@@ -5,7 +5,6 @@ from django.db.models.query_utils import Q
 from django.db.models import Index, Func
 from django.db.models.expressions import BaseExpression, Combinable
 
-
 class PostgresIndex(Index): ...
 
 class BrinIndex(PostgresIndex):

django-stubs/forms/models.pyi

@@ -5,6 +5,7 @@ from typing import (
     Collection,
     Dict,
     Iterator,
+    Generic,
     List,
     Mapping,
     MutableMapping,
@@ -78,8 +79,8 @@ class ModelFormOptions:
 
 class ModelFormMetaclass(DeclarativeFieldsMetaclass): ...
 
-class BaseModelForm(BaseForm):
+class BaseModelForm(Generic[_M], BaseForm):
-    instance: Any = ...
+    instance: _M
     def __init__(
         self,
         data: Optional[Mapping[str, Any]] = ...,
@@ -95,10 +96,10 @@ class BaseModelForm(BaseForm):
         renderer: Any = ...,
     ) -> None: ...
     def validate_unique(self) -> None: ...
-    save_m2m: Any = ...
+    def save(self, commit: bool = ...) -> _M: ...
-    def save(self, commit: bool = ...) -> Any: ...
+    def save_m2m(self) -> None: ...
 
-class ModelForm(BaseModelForm, metaclass=ModelFormMetaclass):
+class ModelForm(BaseModelForm[_M], metaclass=ModelFormMetaclass):
     base_fields: ClassVar[Dict[str, Field]] = ...
 
 def modelform_factory(

django-stubs/views/generic/edit.pyi

@@ -5,14 +5,17 @@ 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.db import models
 
 from django.http import HttpRequest, HttpResponse
 
 _FormT = TypeVar("_FormT", bound=BaseForm)
+_ModelFormT = TypeVar("_ModelFormT", bound=BaseModelForm)
+_T = TypeVar("_T", bound=models.Model)
 
-class AbstractFormMixin(ContextMixin):
+class AbstractFormMixin(Generic[_FormT], ContextMixin):
     initial: Dict[str, Any] = ...
-    form_class: Optional[Type[BaseForm]] = ...
+    form_class: Optional[Type[_FormT]] = ...
     success_url: Optional[Union[str, Callable[..., Any]]] = ...
     prefix: Optional[str] = ...
     def get_initial(self) -> Dict[str, Any]: ...
@@ -26,12 +29,12 @@ class FormMixin(Generic[_FormT], AbstractFormMixin):
     def form_valid(self, form: _FormT) -> HttpResponse: ...
     def form_invalid(self, form: _FormT) -> HttpResponse: ...
 
-class ModelFormMixin(AbstractFormMixin, SingleObjectMixin):
+class ModelFormMixin(Generic[_T, _ModelFormT], AbstractFormMixin, SingleObjectMixin[_T]):
     fields: Optional[Union[Sequence[str], Literal["__all__"]]] = ...
-    def get_form_class(self) -> Type[BaseModelForm]: ...
+    def get_form_class(self) -> Type[_ModelFormT]: ...
-    def get_form(self, form_class: Optional[Type[BaseModelForm]] = ...) -> BaseModelForm: ...
+    def get_form(self, form_class: Optional[Type[_ModelFormT]] = ...) -> BaseModelForm: ...
-    def form_valid(self, form: BaseModelForm) -> HttpResponse: ...
+    def form_valid(self, form: _ModelFormT) -> HttpResponse: ...
-    def form_invalid(self, form: BaseModelForm) -> HttpResponse: ...
+    def form_invalid(self, form: _ModelFormT) -> HttpResponse: ...
 
 class ProcessFormView(View):
     def get(self, request: HttpRequest, *args: str, **kwargs: Any) -> HttpResponse: ...
@@ -40,10 +43,10 @@ class ProcessFormView(View):
 
 class BaseFormView(FormMixin[_FormT], ProcessFormView): ...
 class FormView(TemplateResponseMixin, BaseFormView[_FormT]): ...
-class BaseCreateView(ModelFormMixin, ProcessFormView): ...
+class BaseCreateView(ModelFormMixin[_T, _ModelFormT], ProcessFormView): ...
-class CreateView(SingleObjectTemplateResponseMixin, BaseCreateView): ...
+class CreateView(SingleObjectTemplateResponseMixin, BaseCreateView[_T, _ModelFormT]): ...
-class BaseUpdateView(ModelFormMixin, ProcessFormView): ...
+class BaseUpdateView(ModelFormMixin[_T, _ModelFormT], ProcessFormView): ...
-class UpdateView(SingleObjectTemplateResponseMixin, BaseUpdateView): ...
+class UpdateView(SingleObjectTemplateResponseMixin, BaseUpdateView[_T, _ModelFormT]): ...
 
 class DeletionMixin:
     success_url: Optional[str] = ...

tests/typecheck/views/generic/test_edit.yml

@@ -10,6 +10,8 @@
                 """Ensure that form can have type AuthenticationForm."""
                 form.get_user()
                 return HttpResponseRedirect(self.get_success_url())
+
+
 -   case: dispatch_http_response
     main: |
         from django.http import HttpResponse
@@ -19,6 +21,8 @@
             def dispatch(self, request, *args, **kwargs) -> HttpResponse:
                 response: HttpResponse
                 return response
+
+
 -   case: dispatch_streaming_http_response
     main: |
         from django.http import StreamingHttpResponse
@@ -28,3 +32,32 @@
             def dispatch(self, request, *args, **kwargs) -> StreamingHttpResponse:
                 response: StreamingHttpResponse
                 return response
+
+
+-   case: generic_form_views
+    main: |
+        from django.views.generic.edit import CreateView, UpdateView
+        from django import forms
+        from myapp.models import Article
+
+        class ArticleModelForm(forms.ModelForm[Article]):
+            class Meta:
+                model = Article
+
+        class MyCreateView(CreateView[Article, ArticleModelForm]):
+            def some(self) -> None:
+                reveal_type(self.get_form_class())  # N: Revealed type is "Type[main.ArticleModelForm*]"
+
+        class MyUpdateView(UpdateView[Article, ArticleModelForm]):
+            def some(self) -> None:
+                reveal_type(self.get_form_class()) # N: Revealed type is "Type[main.ArticleModelForm*]"
+    installed_apps:
+        - myapp
+    files:
+        -   path: myapp/__init__.py
+        -   path: myapp/models.py
+            content: |
+                from django.db import models
+
+                class Article(models.Model):
+                    pass