[1.1.X] Fixed #12285. ModelForm raises a more informative error if it doesn't have a model class defined. Backport of [12526] from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.1.X@12530 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/forms/models.py

@@ -214,6 +214,8 @@ class BaseModelForm(BaseForm):
                  empty_permitted=False, instance=None):
         opts = self._meta
         if instance is None:
+            if opts.model is None:
+                raise ValueError('ModelForm has no model class specified.')
             # if we didn't get an instance, instantiate a new one
             self.instance = opts.model()
             object_data = {}

tests/regressiontests/model_forms_regress/tests.py

@@ -100,4 +100,10 @@ class CustomFieldSaveTests(TestCase):
         # It's enough that the form saves without error -- the custom save routine will
         # generate an AssertionError if it is called more than once during save.
         form = CFFForm(data = {'f': None})
-        form.save()
+        form.save()
+
+class ModelClassTests(TestCase):
+    def test_no_model_class(self):
+        class NoModelModelForm(forms.ModelForm):
+            pass
+        self.assertRaises(ValueError, NoModelModelForm)