Allow returning Response from admin @action callbacks (#1331)

Problem: The Django docs say that you can "return an HttpResponse (or subclass) from your action", but the stubs currently say that actions can only return `None`.

Solution: Update stubs to return `HttpResponse | None` instead.

* Fix admin action return type
* Use HttpResponseBase to support StreamingHttpResponse
* Use `T | None` rather than `Optional[T]`
* Add freestanding actions to test
* Add negative test cases

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: christianbundy

django-stubs/contrib/admin/decorators.pyi

@@ -6,7 +6,7 @@ from django.contrib.admin.sites import AdminSite
 from django.db.models import Combinable, QuerySet
 from django.db.models.base import Model
 from django.db.models.expressions import BaseExpression
-from django.http import HttpRequest
+from django.http import HttpRequest, HttpResponseBase
 from django.utils.functional import _StrOrPromise
 from typing_extensions import TypeAlias
 
@@ -17,20 +17,22 @@ _QuerySet = TypeVar("_QuerySet", bound=QuerySet)
 # This is deliberately different from _DisplayT defined in contrib.admin.options
 _DisplayCallable: TypeAlias = Union[Callable[[_ModelAdmin, _Model], Any], Callable[[_Model], Any]]  # noqa: Y037
 _DisplayCallableT = TypeVar("_DisplayCallableT", bound=_DisplayCallable)
+_ActionReturn = TypeVar("_ActionReturn", bound=HttpResponseBase | None)
 
 @overload
 def action(
-    function: Callable[[_ModelAdmin, _Request, _QuerySet], None],
+    function: Callable[[_ModelAdmin, _Request, _QuerySet], _ActionReturn],
     permissions: Sequence[str] | None = ...,
     description: _StrOrPromise | None = ...,
-) -> Callable[[_ModelAdmin, _Request, _QuerySet], None]: ...
+) -> Callable[[_ModelAdmin, _Request, _QuerySet], _ActionReturn]: ...
 @overload
 def action(
     *,
     permissions: Sequence[str] | None = ...,
     description: _StrOrPromise | None = ...,
 ) -> Callable[
-    [Callable[[_ModelAdmin, _Request, _QuerySet], None]], Callable[[_ModelAdmin, _Request, _QuerySet], None]
+    [Callable[[_ModelAdmin, _Request, _QuerySet], _ActionReturn]],
+    Callable[[_ModelAdmin, _Request, _QuerySet], _ActionReturn],
 ]: ...
 @overload
 def display(

django-stubs/contrib/admin/options.pyi

@@ -27,7 +27,7 @@ from django.forms.models import (
 )
 from django.forms.widgets import Media
 from django.http.request import HttpRequest
-from django.http.response import HttpResponse, HttpResponseRedirect
+from django.http.response import HttpResponse, HttpResponseBase, HttpResponseRedirect
 from django.template.response import _TemplateForResponseT
 from django.urls.resolvers import URLPattern
 from django.utils.datastructures import _ListOrTuple
@@ -131,7 +131,7 @@ class BaseModelAdmin(Generic[_ModelT]):
 
 _DisplayT: TypeAlias = _ListOrTuple[str | Callable[[_ModelT], str | bool]]
 _ModelAdmin = TypeVar("_ModelAdmin", bound=ModelAdmin)
-_ActionCallable: TypeAlias = Callable[[_ModelAdmin, HttpRequest, QuerySet[_ModelT]], None]
+_ActionCallable: TypeAlias = Callable[[_ModelAdmin, HttpRequest, QuerySet[_ModelT]], HttpResponseBase | None]
 
 class ModelAdmin(BaseModelAdmin[_ModelT]):
     list_display: _DisplayT

tests/typecheck/contrib/admin/test_decorators.yml

@@ -60,7 +60,7 @@
 
     from django.contrib import admin
     from django.db.models import QuerySet
-    from django.http import HttpRequest
+    from django.http import FileResponse, HttpRequest, HttpResponse
 
 
     class MyModel(models.Model): ...
@@ -73,17 +73,42 @@
     @admin.action(description="Some text here", permissions=["test"])
     def freestanding_action_fancy(modeladmin: "MyModelAdmin", request: HttpRequest, queryset: QuerySet[MyModel]) -> None: ...
 
+    @admin.action
+    def freestanding_action_http_response(modeladmin: "MyModelAdmin", request: HttpRequest, queryset: QuerySet[MyModel]) -> HttpResponse: ...
+
+    @admin.action
+    def freestanding_action_file_response(modeladmin: "MyModelAdmin", request: HttpRequest, queryset: QuerySet[MyModel]) -> FileResponse: ...
+
+    @admin.action # E: Value of type variable "_ModelAdmin" of "action" cannot be "int"
+    def freestanding_action_invalid_bare(modeladmin: int, request: HttpRequest, queryset: QuerySet[MyModel]) -> None: ...
+
+    @admin.action(description="Some text here", permissions=["test"]) # E: Value of type variable "_ModelAdmin" of function cannot be "int"
+    def freestanding_action_invalid_fancy(modeladmin: int, request: HttpRequest, queryset: QuerySet[MyModel]) -> None: ...
 
     @admin.register(MyModel)
     class MyModelAdmin(admin.ModelAdmin[MyModel]):
-        actions = [freestanding_action_bare, freestanding_action_fancy, "method_action_bare", "method_action_fancy"]
+        actions = [freestanding_action_bare, freestanding_action_fancy, "method_action_bare", "method_action_fancy", freestanding_action_http_response, freestanding_action_file_response]
 
         @admin.action
         def method_action_bare(self, request: HttpRequest, queryset: QuerySet[MyModel]) -> None: ...
 
         @admin.action(description="Some text here", permissions=["test"])
         def method_action_fancy(self, request: HttpRequest, queryset: QuerySet[MyModel]) -> None: ...
 
+        @admin.action(description="Some text here", permissions=["test"])
+        def method_action_http_response(self, request: HttpRequest, queryset: QuerySet[MyModel]) -> HttpResponse: ...
+
+        @admin.action(description="Some text here", permissions=["test"])
+        def method_action_file_response(self, request: HttpRequest, queryset: QuerySet[MyModel]) -> FileResponse: ...
+
+        @admin.action  # E: Value of type variable "_QuerySet" of "action" cannot be "int"
+        def method_action_invalid_bare(self, request: HttpRequest, queryset: int) -> None: ...
+
+        @admin.action(description="Some text here", permissions=["test"])  # E: Value of type variable "_QuerySet" of function cannot be "int"
+        def method_action_invalid_fancy(self, request: HttpRequest, queryset: int) -> None: ...
+
         def method(self) -> None:
             reveal_type(self.method_action_bare)  # N: Revealed type is "def (django.http.request.HttpRequest, django.db.models.query._QuerySet[main.MyModel, main.MyModel])"
             reveal_type(self.method_action_fancy)  # N: Revealed type is "def (django.http.request.HttpRequest, django.db.models.query._QuerySet[main.MyModel, main.MyModel])"
+            reveal_type(self.method_action_http_response)  # N: Revealed type is "def (django.http.request.HttpRequest, django.db.models.query._QuerySet[main.MyModel, main.MyModel]) -> django.http.response.HttpResponse"
+            reveal_type(self.method_action_file_response)  # N: Revealed type is "def (django.http.request.HttpRequest, django.db.models.query._QuerySet[main.MyModel, main.MyModel]) -> django.http.response.FileResponse"

tests/typecheck/contrib/admin/test_options.yml

@@ -140,7 +140,7 @@
           pass
 
       class A(admin.ModelAdmin):
-          actions = [an_action]  # E: List item 0 has incompatible type "Callable[[None], None]"; expected "Union[Callable[[Any, HttpRequest, _QuerySet[Any, Any]], None], str]"
+          actions = [an_action]  # E: List item 0 has incompatible type "Callable[[None], None]"; expected "Union[Callable[[Any, HttpRequest, _QuerySet[Any, Any]], Optional[HttpResponseBase]], str]"
 -   case: errors_for_invalid_model_admin_generic
     main: |
       from django.contrib.admin import ModelAdmin