Fixed #28387 -- Fixed has_changed() for disabled form fields that subclass it.

django/forms/fields.py

@@ -586,6 +586,8 @@ class FileField(Field):
         return data
 
     def has_changed(self, initial, data):
+        if self.disabled:
+            return False
         if data is None:
             return False
         return True
@@ -706,6 +708,8 @@ class BooleanField(Field):
             raise ValidationError(self.error_messages['required'], code='required')
 
     def has_changed(self, initial, data):
+        if self.disabled:
+            return False
         # Sometimes data or initial may be a string equivalent of a boolean
         # so we should run it through to_python first to get a boolean value
         return self.to_python(initial) != self.to_python(data)
@@ -864,6 +868,8 @@ class MultipleChoiceField(ChoiceField):
                 )
 
     def has_changed(self, initial, data):
+        if self.disabled:
+            return False
         if initial is None:
             initial = []
         if data is None:
@@ -1042,6 +1048,8 @@ class MultiValueField(Field):
         raise NotImplementedError('Subclasses must implement this method.')
 
     def has_changed(self, initial, data):
+        if self.disabled:
+            return False
         if initial is None:
             initial = ['' for x in range(0, len(data))]
         else:

django/forms/models.py

@@ -1250,6 +1250,8 @@ class ModelChoiceField(ChoiceField):
         return Field.validate(self, value)
 
     def has_changed(self, initial, data):
+        if self.disabled:
+            return False
         initial_value = initial if initial is not None else ''
         data_value = data if data is not None else ''
         return str(self.prepare_value(initial_value)) != str(data_value)
@@ -1334,6 +1336,8 @@ class ModelMultipleChoiceField(ModelChoiceField):
         return super().prepare_value(value)
 
     def has_changed(self, initial, data):
+        if self.disabled:
+            return False
         if initial is None:
             initial = []
         if data is None:

docs/releases/1.11.4.txt

@@ -21,3 +21,7 @@ Bugfixes
 
 * Fixed crash in ``runserver``'s ``autoreload`` with Python 2 on Windows with
   non-``str`` environment variables (:ticket:`28174`).
+
+* Corrected ``Field.has_changed()`` to return ``False`` for disabled form
+  fields: ``BooleanField``, ``MultipleChoiceField``, ``MultiValueField``,
+  ``FileField``, ``ModelChoiceField``, and ``ModelMultipleChoiceField``.

tests/forms_tests/field_tests/test_booleanfield.py

@@ -57,3 +57,7 @@ class BooleanFieldTest(SimpleTestCase):
         self.assertFalse(f.has_changed(True, 'True'))
         self.assertTrue(f.has_changed(False, 'True'))
         self.assertTrue(f.has_changed(True, 'False'))
+
+    def test_disabled_has_changed(self):
+        f = BooleanField(disabled=True)
+        self.assertIs(f.has_changed('True', 'False'), False)

tests/forms_tests/field_tests/test_filefield.py

@@ -74,5 +74,9 @@ class FileFieldTest(SimpleTestCase):
         # with here)
         self.assertTrue(f.has_changed('resume.txt', {'filename': 'resume.txt', 'content': 'My resume'}))
 
+    def test_disabled_has_changed(self):
+        f = FileField(disabled=True)
+        self.assertIs(f.has_changed('x', 'y'), False)
+
     def test_file_picklable(self):
         self.assertIsInstance(pickle.loads(pickle.dumps(FileField())), FileField)

tests/forms_tests/field_tests/test_multiplechoicefield.py

@@ -68,3 +68,7 @@ class MultipleChoiceFieldTest(SimpleTestCase):
         self.assertFalse(f.has_changed([2, 1], ['1', '2']))
         self.assertTrue(f.has_changed([1, 2], ['1']))
         self.assertTrue(f.has_changed([1, 2], ['1', '3']))
+
+    def test_disabled_has_changed(self):
+        f = MultipleChoiceField(choices=[('1', 'One'), ('2', 'Two')], disabled=True)
+        self.assertIs(f.has_changed('x', 'y'), False)

tests/forms_tests/field_tests/test_multivaluefield.py

@@ -103,6 +103,10 @@ class MultiValueFieldTest(SimpleTestCase):
             ['some text', ['J', 'P'], ['2009-04-25', '11:44:00']],
         ))
 
+    def test_disabled_has_changed(self):
+        f = MultiValueField(fields=(CharField(), CharField()), disabled=True)
+        self.assertIs(f.has_changed(['x', 'x'], ['y', 'y']), False)
+
     def test_form_as_table(self):
         form = ComplexFieldForm()
         self.assertHTMLEqual(

tests/model_forms/tests.py

@@ -1702,6 +1702,10 @@ class ModelChoiceFieldTests(TestCase):
             ['Select a valid choice. That choice is not one of the available choices.']
         )
 
+    def test_disabled_modelchoicefield_has_changed(self):
+        field = forms.ModelChoiceField(Author.objects.all(), disabled=True)
+        self.assertIs(field.has_changed('x', 'y'), False)
+
     def test_disabled_multiplemodelchoicefield(self):
         class ArticleForm(forms.ModelForm):
             categories = forms.ModelMultipleChoiceField(Category.objects.all(), required=False)
@@ -1727,6 +1731,10 @@ class ModelChoiceFieldTests(TestCase):
         self.assertEqual(form.errors, {})
         self.assertEqual([x.pk for x in form.cleaned_data['categories']], [category1.pk])
 
+    def test_disabled_modelmultiplechoicefield_has_changed(self):
+        field = forms.ModelMultipleChoiceField(Author.objects.all(), disabled=True)
+        self.assertIs(field.has_changed('x', 'y'), False)
+
     def test_modelchoicefield_iterator(self):
         """
         Iterator defaults to ModelChoiceIterator and can be overridden with