Refs #26220 -- Added SingleObjectMixin._get_model().

AUTHORS

@@ -233,6 +233,7 @@ answer newbie questions, and generally made Django that much better:
     Chris Wilson <chris+github@qwirx.com>
     Ciaran McCormick <ciaran@ciaranmccormick.com>
     Claude Paroz <claude@2xlibre.net>
+    Clifford Gama <cliffygamy@gmail.com>
     Clint Ecker
     colin@owlfish.com
     Colin Wood <cwood06@gmail.com>

django/views/generic/detail.py

@@ -66,8 +66,8 @@ class SingleObjectMixin(ContextMixin):
         may not be called if get_object() is overridden.
         """
         if self.queryset is None:
-            if self.model:
+            if (model := self._get_model()) is not None:
-                return self.model._default_manager.all()
+                return model._default_manager.all()
             else:
                 raise ImproperlyConfigured(
                     "%(cls)s is missing a QuerySet. Define "
@@ -76,6 +76,13 @@ class SingleObjectMixin(ContextMixin):
                 )
         return self.queryset.all()
 
+    def _get_model(self):
+        """Return the model of the object the view is displaying."""
+        model = self.model
+        if model is None and getattr(self, "object", None) is not None:
+            return self.object.__class__
+        return model
+
     def get_slug_field(self):
         """Get the name of a slug field to be used to look up by slug."""
         return self.slug_field
@@ -155,14 +162,14 @@ class SingleObjectTemplateResponseMixin(TemplateResponseMixin):
                         self.template_name_suffix,
                     )
                 )
-            elif getattr(self, "model", None) is not None and issubclass(
+            elif (model := getattr(self, "_get_model", lambda: None)()) and issubclass(
-                self.model, models.Model
+                model, models.Model
             ):
                 names.append(
                     "%s/%s%s.html"
                     % (
-                        self.model._meta.app_label,
+                        model._meta.app_label,
-                        self.model._meta.model_name,
+                        model._meta.model_name,
                         self.template_name_suffix,
                     )
                 )

django/views/generic/edit.py

@@ -87,18 +87,7 @@ class ModelFormMixin(FormMixin, SingleObjectMixin):
         if self.form_class:
             return self.form_class
         else:
-            if self.model is not None:
+            model = self._get_model() or self.get_queryset().model
-                # If a model has been explicitly provided, use it
-                model = self.model
-            elif getattr(self, "object", None) is not None:
-                # If this view is operating on a single object, use
-                # the class of that object
-                model = self.object.__class__
-            else:
-                # Try to get a queryset and extract the model class
-                # from that
-                model = self.get_queryset().model
-
             if self.fields is None:
                 raise ImproperlyConfigured(
                     "Using ModelFormMixin (base class of %s) without "

docs/releases/5.2.txt

@@ -226,7 +226,10 @@ Forms
 Generic Views
 ~~~~~~~~~~~~~
 
-* ...
+* The new :meth:`~django.views.generic.detail.SingleObjectMixin._get_model`
+  method returns the model defined for the view, or a custom model if
+  overridden. If ``queryset`` is provided, it takes precedence as the source
+  of objects.
 
 Internationalization
 ~~~~~~~~~~~~~~~~~~~~

tests/generic_views/test_detail.py

@@ -219,3 +219,48 @@ class DetailViewTest(TestCase):
         res = self.client.get("/detail/nonmodel/1/")
         self.assertEqual(res.status_code, 200)
         self.assertEqual(res.context["object"].id, "non_model_1")
+
+    def test_get_model_override(self):
+        res = self.client.get("/detail/author/getmodel/%s/" % self.author1.pk)
+        self.assertEqual(res.status_code, 200)
+        self.assertEqual(res.context["object"], self.author1)
+        self.assertTemplateUsed(res, "generic_views/author_detail.html")
+
+    def test_invalid_model_configuration(self):
+        msg = (
+            "MissingModelView is missing a QuerySet. Define MissingModelView.model, "
+            "MissingModelView.queryset, or override MissingModelView.get_queryset()."
+        )
+        with self.assertRaisesMessage(ImproperlyConfigured, msg):
+            self.client.get("/missing-model/")
+
+    def test_conflicting_model_and_get_model(self):
+        """
+        `_get_model` takes precedence over model.
+        """
+        url = "/detail/conflicting-model-and-getmodel/%s/" % self.author1.pk
+        res = self.client.get(url)
+        self.assertEqual(res.status_code, 200)
+        self.assertEqual(res.context["object"], self.author1)
+        self.assertTemplateUsed(res, "generic_views/author_detail.html")
+
+    def test_model_and_queryset_ignores_model(self):
+        """
+        Queryset takes precedence over model as source of objects.
+        """
+        url = "/detail/author/conflicting-model-and-queryset/%s/" % self.author1.pk
+        res = self.client.get(url)
+        self.assertEqual(res.status_code, 200)
+        self.assertEqual(res.context["object"], self.author1)
+        self.assertTemplateUsed(res, "generic_views/author_detail.html")
+
+    def test_queryset_and_get_model_ignores_get_model(self):
+        """
+        When queryset is defined, it takes precedence over `_get_model` as
+        source of model objects.
+        """
+        url = "/detail/conflicting-queryset-and-getmodel/%s/" % self.artist1.pk
+        res = self.client.get(url)
+        self.assertEqual(res.status_code, 200)
+        self.assertEqual(res.context["object"], self.artist1)
+        self.assertTemplateUsed(res, "generic_views/artist_detail.html")

tests/generic_views/urls.py

@@ -5,7 +5,7 @@ from django.views.decorators.cache import cache_page
 from django.views.generic import TemplateView, dates
 
 from . import views
-from .models import Book
+from .models import Artist, Book
 
 urlpatterns = [
     # TemplateView
@@ -75,6 +75,23 @@ urlpatterns = [
     path("detail/author/invalid/qs/", views.AuthorDetail.as_view(queryset=None)),
     path("detail/nonmodel/1/", views.NonModelDetail.as_view()),
     path("detail/doesnotexist/<pk>/", views.ObjectDoesNotExistDetail.as_view()),
+    path(
+        "detail/author/getmodel/<int:pk>/",
+        views.AuthorDetailOverridesGetModel.as_view(),
+    ),
+    path("missing-model/", views.MissingModelView.as_view()),
+    path(
+        "detail/conflicting-model-and-getmodel/<int:pk>/",
+        views.AuthorDetailOverridesGetModel.as_view(model=Artist),
+    ),
+    path(
+        "detail/author/conflicting-model-and-queryset/<int:pk>/",
+        views.AuthorDetailConflictingModelAndQueryset.as_view(),
+    ),
+    path(
+        "detail/conflicting-queryset-and-getmodel/<int:pk>/",
+        views.AuthorDetailOverridesGetModel.as_view(queryset=Artist.objects.all()),
+    ),
     # FormView
     path("contact/", views.ContactView.as_view()),
     path("late-validation/", views.LateValidationView.as_view()),

tests/generic_views/views.py

@@ -43,6 +43,20 @@ class AuthorCustomDetail(generic.DetailView):
         return self.render_to_response(context)
 
 
+class AuthorDetailOverridesGetModel(generic.DetailView):
+    def _get_model(self):
+        return Author
+
+
+class AuthorDetailConflictingModelAndQueryset(generic.DetailView):
+    queryset = Author.objects.all()
+    model = Artist
+
+
+class MissingModelView(generic.DetailView):
+    pass
+
+
 class PageDetail(generic.DetailView):
     queryset = Page.objects.all()
     template_name_field = "template"