diff --git a/django/forms/fields.py b/django/forms/fields.py index 55f225e65b..ac615bbe68 100644 --- a/django/forms/fields.py +++ b/django/forms/fields.py @@ -181,17 +181,16 @@ class Field(object): """ Return True if data differs from initial. """ - # For purposes of seeing whether something has changed, None is - # the same as an empty string, if the data or initial value we get - # is None, replace it w/ ''. - initial_value = initial if initial is not None else '' try: data = self.to_python(data) if hasattr(self, '_coerce'): - data = self._coerce(data) - initial_value = self._coerce(initial_value) + return self._coerce(data) != self._coerce(initial) except ValidationError: return True + # For purposes of seeing whether something has changed, None is + # the same as an empty string, if the data or initial value we get + # is None, replace it with ''. + initial_value = initial if initial is not None else '' data_value = data if data is not None else '' return initial_value != data_value diff --git a/docs/releases/1.9.1.txt b/docs/releases/1.9.1.txt index 25acbd540b..20fd723d2b 100644 --- a/docs/releases/1.9.1.txt +++ b/docs/releases/1.9.1.txt @@ -43,3 +43,6 @@ Bugfixes * Fixed a state bug when using an ``AlterModelManagers`` operation (:ticket:`25852`). + +* Fixed ``TypedChoiceField`` change detection with nullable fields + (:ticket:`25942`). diff --git a/tests/forms_tests/tests/test_fields.py b/tests/forms_tests/tests/test_fields.py index 42e7bc91f7..7fae0bdfc2 100644 --- a/tests/forms_tests/tests/test_fields.py +++ b/tests/forms_tests/tests/test_fields.py @@ -1246,6 +1246,14 @@ class FieldsTests(SimpleTestCase): self.assertFalse(f.has_changed(1, '1')) self.assertFalse(f.has_changed('1', '1')) + f = TypedChoiceField( + choices=[('', '---------'), ('a', "a"), ('b', "b")], coerce=six.text_type, + required=False, initial=None, empty_value=None, + ) + self.assertFalse(f.has_changed(None, '')) + self.assertTrue(f.has_changed('', 'a')) + self.assertFalse(f.has_changed('a', 'a')) + def test_typedchoicefield_special_coerce(self): """ Test a coerce function which results in a value not present in choices.