Ticket #15877: 0001-Fixes-15877-ModelForm-will-raise-ValueError-if-not-M.patch

django/forms/models.py

@@ -227 +227 @@
                  initial=None, error_class=ErrorList, label_suffix=':',
                  empty_permitted=False, instance=None):
         opts = self._meta
+        if opts.model is None:
+            raise ValueError('ModelForm has no model class specified.')
         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/modeltests/model_forms/tests.py

@@ -124 +124 @@
         model = CustomFieldForExclusionModel
         fields = ['name', 'markup']
 
-class ShortCategory(forms.ModelForm):
-    name = forms.CharField(max_length=5)
-    slug = forms.CharField(max_length=5)
-    url = forms.CharField(max_length=3)
-
 class ImprovedArticleForm(forms.ModelForm):
     class Meta:
         model = ImprovedArticle
@@ -181 +176 @@
         self.assertEqual(BaseCategoryForm.base_fields.keys(),
                          ['name', 'slug', 'url'])
 
+    def test_invalid_meta_model(self):
+        class InvalidModelForm(forms.ModelForm):
+            class Meta:
+                pass # no model.
+        # can't create new form
+        with self.assertRaises(ValueError):
+            f = InvalidModelForm()
+        # even if you provide a model instance
+        with self.assertRaises(ValueError):
+            f = InvalidModelForm(instance=Category)
+
     def test_extra_fields(self):
         class ExtraFields(BaseCategoryForm):
             some_extra_field = forms.BooleanField()
@@ -863 +869 @@
         f.save_m2m()
         self.assertEqual(map(lambda o: o.name, new_art.categories.order_by('name')), ["Entertainment", "It's a test"])
 
-        # Here, we define a custom ModelForm. Because it happens to have the same fields as
-        # the Category model, we can just call the form's save() to apply its changes to an
-        # existing Category instance.
-        cat = Category.objects.get(name='Third test')
-        self.assertEqual(cat.name, "Third test")
-        self.assertEqual(cat.id == c3.id, True)
-        form = ShortCategory({'name': 'Third', 'slug': 'third', 'url': '3rd'}, instance=cat)
-        self.assertEqual(form.save().name, 'Third')
-        self.assertEqual(Category.objects.get(id=c3.id).name, 'Third')
-
         # Here, we demonstrate that choices for a ForeignKey ChoiceField are determined
         # at runtime, based on the data in the database when the form is displayed, not
         # the data in the database when the form is instantiated.