Ticket #12215: modelchoice_iterator_len.diff

django/forms/models.py

@@ -910 +910 @@
             for obj in self.queryset.all():
                 yield self.choice(obj)
 
+    def __len__(self):
+        return len(self.queryset)
+
     def choice(self, obj):
         if self.field.to_field_name:
             key = obj.serializable_value(self.field.to_field_name)
         else:
             key = obj.pk
         return (key, self.field.label_from_instance(obj))
+    
 
 
 class ModelChoiceField(ChoiceField):

tests/regressiontests/model_forms_regress/tests.py

@@ -100 +100 @@
         # 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()
- No newline at end of file
+        form.save()
+
+
+class ModelChoiceIteratorTests(TestCase):
+    def test_len(self):
+        class Form(forms.ModelForm):
+            class Meta:
+                model = Article
+                fields = ["publications"]
+        
+        Publication.objects.create(title="Pravda",
+            date_published=date(1991, 8, 22))
+        f = Form()
+        self.assertEqual(len(f.fields["publications"].choices), 1)