Fixed #15722: ensure formsets evaluate to True even if they have no forms. Thanks mlavin.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@16756 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/forms/formsets.py

@@ -60,6 +60,10 @@ class BaseFormSet(StrAndUnicode):
     def __len__(self):
         return len(self.forms)
 
+    def __nonzero__(self):
+        """All formsets have a management form which is not included in the length"""
+        return True
+
     def _management_form(self):
         """Returns the ManagementForm instance for this FormSet."""
         if self.is_bound:

tests/regressiontests/forms/tests/formsets.py

@@ -805,6 +805,17 @@ class FormsFormsetTestCase(TestCase):
         self.assertEqual(str(reverse_formset[1]), str(forms[-2]))
         self.assertEqual(len(reverse_formset), len(forms))
 
+    def test_formset_nonzero(self):
+        """
+        Formsets with no forms should still evaluate as true.
+        Regression test for #15722
+        """
+        ChoiceFormset = formset_factory(Choice, extra=0)
+        formset = ChoiceFormset()
+        self.assertEqual(len(formset.forms), 0)
+        self.assertTrue(formset)
+
+
 data = {
     'choices-TOTAL_FORMS': '1', # the number of forms rendered
     'choices-INITIAL_FORMS': '0', # the number of forms with initial data