Fix #26220 -- Allowed ModelFormMixin._get_model() to retrieve the model from form_class's Meta.

django/views/generic/edit.py

@@ -1,5 +1,5 @@
 from django.core.exceptions import ImproperlyConfigured
-from django.forms import Form
+from django.forms import Form, ModelForm
 from django.forms import models as model_forms
 from django.http import HttpResponseRedirect
 from django.views.generic.base import ContextMixin, TemplateResponseMixin, View
@@ -103,6 +103,13 @@ class ModelFormMixin(FormMixin, SingleObjectMixin):
             kwargs.update({"instance": self.object})
         return kwargs
 
+    def _get_model(self):
+        model = super()._get_model()
+        if model is None and self.form_class is not None:
+            if issubclass(self.form_class, ModelForm):
+                model = self.form_class.Meta.model
+        return model
+
     def get_success_url(self):
         """Return the URL to redirect to after processing a valid form."""
         if self.success_url:

docs/releases/5.2.txt

@@ -231,6 +231,11 @@ Generic Views
   overridden. If ``queryset`` is provided, it takes precedence as the source
   of objects.
 
+* The new :meth:`~django.views.generic.detail.SingleObjectMixin._get_model`
+  method is overridden in :class:`~django.views.generic.edit.ModelFormMixin`
+  to allow `ModelFormMixin` to retrive the view's `model` from the `form_class`
+  if a `ModelForm` is specified for `form_class`.
+
 Internationalization
 ~~~~~~~~~~~~~~~~~~~~
 

tests/generic_views/test_edit.py

@@ -164,7 +164,7 @@ class CreateViewTests(TestCase):
         self.assertIsInstance(res.context["form"], views.AuthorForm)
         self.assertNotIn("object", res.context)
         self.assertNotIn("author", res.context)
-        self.assertTemplateUsed(res, "generic_views/form.html")
+        self.assertTemplateUsed(res, "generic_views/author_form.html")
 
         res = self.client.post(
             "/edit/authors/create/special/",
@@ -324,7 +324,7 @@ class UpdateViewTests(TestCase):
         self.assertEqual(res.context["object"], self.author)
         self.assertEqual(res.context["thingy"], self.author)
         self.assertNotIn("author", res.context)
-        self.assertTemplateUsed(res, "generic_views/form.html")
+        self.assertTemplateUsed(res, "generic_views/author_form.html")
 
         res = self.client.post(
             "/edit/author/%d/update/special/" % self.author.pk,

tests/generic_views/views.py

@@ -144,9 +144,7 @@ class AuthorCreate(generic.CreateView):
 
 
 class SpecializedAuthorCreate(generic.CreateView):
-    model = Author
     form_class = AuthorForm
-    template_name = "generic_views/form.html"
     context_object_name = "thingy"
 
     def get_success_url(self):
@@ -187,9 +185,7 @@ class OneAuthorUpdate(generic.UpdateView):
 
 
 class SpecializedAuthorUpdate(generic.UpdateView):
-    model = Author
     form_class = AuthorForm
-    template_name = "generic_views/form.html"
     context_object_name = "thingy"
 
     def get_success_url(self):