Moved has_changed logic from widget to form field

Refs #16612. Thanks Aymeric Augustin for the suggestion.

14 files changed, 230 insertions, 251 deletions

diff --git a/django/contrib/admin/widgets.py b/django/contrib/admin/widgets.py
index 1e6277fb87..a3887740d8 100644
--- a/django/contrib/admin/widgets.py
+++ b/django/contrib/admin/widgets.py
@@ -213,17 +213,6 @@ class ManyToManyRawIdWidget(ForeignKeyRawIdWidget):
         if value:
             return value.split(',')
 
-    def _has_changed(self, initial, data):
-        if initial is None:
-            initial = []
-        if data is None:
-            data = []
-        if len(initial) != len(data):
-            return True
-        for pk1, pk2 in zip(initial, data):
-            if force_text(pk1) != force_text(pk2):
-                return True
-        return False
 
 class RelatedFieldWidgetWrapper(forms.Widget):
     """
@@ -279,9 +268,6 @@ class RelatedFieldWidgetWrapper(forms.Widget):
     def value_from_datadict(self, data, files, name):
         return self.widget.value_from_datadict(data, files, name)
 
-    def _has_changed(self, initial, data):
-        return self.widget._has_changed(initial, data)
-
     def id_for_label(self, id_):
         return self.widget.id_for_label(id_)
 
diff --git a/django/contrib/gis/admin/widgets.py b/django/contrib/gis/admin/widgets.py
index f4379be7f3..a06933660f 100644
--- a/django/contrib/gis/admin/widgets.py
+++ b/django/contrib/gis/admin/widgets.py
@@ -7,7 +7,7 @@ from django.utils import six
 from django.utils import translation
 
 from django.contrib.gis.gdal import OGRException
-from django.contrib.gis.geos import GEOSGeometry, GEOSException, fromstr
+from django.contrib.gis.geos import GEOSGeometry, GEOSException
 
 # Creating a template context that contains Django settings
 # values needed by admin map templates.
@@ -117,25 +117,3 @@ class OpenLayersWidget(Textarea):
                     raise TypeError
                 map_options[js_name] = value
         return map_options
-
-    def _has_changed(self, initial, data):
-        """ Compare geographic value of data with its initial value. """
-
-        # Ensure we are dealing with a geographic object
-        if isinstance(initial, six.string_types):
-            try:
-                initial = GEOSGeometry(initial)
-            except (GEOSException, ValueError):
-                initial = None
-
-        # Only do a geographic comparison if both values are available
-        if initial and data:
-            data = fromstr(data)
-            data.transform(initial.srid)
-            # If the initial value was not added by the browser, the geometry
-            # provided may be slightly different, the first time it is saved.
-            # The comparison is done with a very low tolerance.
-            return not initial.equals_exact(data, tolerance=0.000001)
-        else:
-            # Check for change of state of existence
-            return bool(initial) != bool(data)
diff --git a/django/contrib/gis/forms/fields.py b/django/contrib/gis/forms/fields.py
index cefb6830ba..ab2e37f1e1 100644
--- a/django/contrib/gis/forms/fields.py
+++ b/django/contrib/gis/forms/fields.py
@@ -1,11 +1,13 @@
 from __future__ import unicode_literals
 
 from django import forms
+from django.utils import six
 from django.utils.translation import ugettext_lazy as _
 
 # While this couples the geographic forms to the GEOS library,
 # it decouples from database (by not importing SpatialBackend).
-from django.contrib.gis.geos import GEOSException, GEOSGeometry
+from django.contrib.gis.geos import GEOSException, GEOSGeometry, fromstr
+
 
 class GeometryField(forms.Field):
     """
@@ -73,3 +75,25 @@ class GeometryField(forms.Field):
                     raise forms.ValidationError(self.error_messages['transform_error'])
 
         return geom
+
+    def _has_changed(self, initial, data):
+        """ Compare geographic value of data with its initial value. """
+
+        # Ensure we are dealing with a geographic object
+        if isinstance(initial, six.string_types):
+            try:
+                initial = GEOSGeometry(initial)
+            except (GEOSException, ValueError):
+                initial = None
+
+        # Only do a geographic comparison if both values are available
+        if initial and data:
+            data = fromstr(data)
+            data.transform(initial.srid)
+            # If the initial value was not added by the browser, the geometry
+            # provided may be slightly different, the first time it is saved.
+            # The comparison is done with a very low tolerance.
+            return not initial.equals_exact(data, tolerance=0.000001)
+        else:
+            # Check for change of state of existence
+            return bool(initial) != bool(data)
diff --git a/django/contrib/gis/tests/geoadmin/tests.py b/django/contrib/gis/tests/geoadmin/tests.py
index 6fadebdb9a..669914bdea 100644
--- a/django/contrib/gis/tests/geoadmin/tests.py
+++ b/django/contrib/gis/tests/geoadmin/tests.py
@@ -38,7 +38,7 @@ class GeoAdminTest(TestCase):
         """ Check that changes are accurately noticed by OpenLayersWidget. """
         geoadmin = admin.site._registry[City]
         form = geoadmin.get_changelist_form(None)()
-        has_changed = form.fields['point'].widget._has_changed
+        has_changed = form.fields['point']._has_changed
 
         initial = Point(13.4197458572965953, 52.5194108501149799, srid=4326)
         data_same = "SRID=3857;POINT(1493879.2754093995 6894592.019687599)"
diff --git a/django/forms/extras/widgets.py b/django/forms/extras/widgets.py
index c5ca1424c8..e939a8f665 100644
--- a/django/forms/extras/widgets.py
+++ b/django/forms/extras/widgets.py
@@ -135,11 +135,3 @@ class SelectDateWidget(Widget):
         s = Select(choices=choices)
         select_html = s.render(field % name, val, local_attrs)
         return select_html
-
-    def _has_changed(self, initial, data):
-        try:
-            input_format = get_format('DATE_INPUT_FORMATS')[0]
-            data = datetime_safe.datetime.strptime(data, input_format).date()
-        except (TypeError, ValueError):
-            pass
-        return super(SelectDateWidget, self)._has_changed(initial, data)
diff --git a/django/forms/fields.py b/django/forms/fields.py
index 4438812a37..1e9cbcb4d9 100644
--- a/django/forms/fields.py
+++ b/django/forms/fields.py
@@ -175,6 +175,25 @@ class Field(object):
         """
         return {}
 
+    def _has_changed(self, initial, data):
+        """
+        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 inital value we get
+        # is None, replace it w/ ''.
+        if data is None:
+            data_value = ''
+        else:
+            data_value = data
+        if initial is None:
+            initial_value = ''
+        else:
+            initial_value = initial
+        if force_text(initial_value) != force_text(data_value):
+            return True
+        return False
+
     def __deepcopy__(self, memo):
         result = copy.copy(self)
         memo[id(self)] = result
@@ -348,6 +367,13 @@ class BaseTemporalField(Field):
     def strptime(self, value, format):
         raise NotImplementedError('Subclasses must define this method.')
 
+    def _has_changed(self, initial, data):
+        try:
+            data = self.to_python(data)
+        except ValidationError:
+            return True
+        return self.to_python(initial) != data
+
 class DateField(BaseTemporalField):
     widget = DateInput
     input_formats = formats.get_format_lazy('DATE_INPUT_FORMATS')
@@ -371,6 +397,7 @@ class DateField(BaseTemporalField):
     def strptime(self, value, format):
         return datetime.datetime.strptime(value, format).date()
 
+
 class TimeField(BaseTemporalField):
     widget = TimeInput
     input_formats = formats.get_format_lazy('TIME_INPUT_FORMATS')
@@ -529,6 +556,12 @@ class FileField(Field):
             return initial
         return data
 
+    def _has_changed(self, initial, data):
+        if data is None:
+            return False
+        return True
+
+
 class ImageField(FileField):
     default_error_messages = {
         'invalid_image': _("Upload a valid image. The file you uploaded was either not an image or a corrupted image."),
@@ -618,6 +651,7 @@ class URLField(CharField):
             value = urlunsplit(url_fields)
         return value
 
+
 class BooleanField(Field):
     widget = CheckboxInput
 
@@ -636,6 +670,15 @@ class BooleanField(Field):
             raise ValidationError(self.error_messages['required'])
         return value
 
+    def _has_changed(self, initial, data):
+        # Sometimes data or initial could be None or '' which should be the
+        # same thing as False.
+        if initial == 'False':
+            # show_hidden_initial may have transformed False to 'False'
+            initial = False
+        return bool(initial) != bool(data)
+
+
 class NullBooleanField(BooleanField):
     """
     A field whose valid values are None, True and False. Invalid values are
@@ -660,6 +703,15 @@ class NullBooleanField(BooleanField):
     def validate(self, value):
         pass
 
+    def _has_changed(self, initial, data):
+        # None (unknown) and False (No) are not the same
+        if initial is not None:
+            initial = bool(initial)
+        if data is not None:
+            data = bool(data)
+        return initial != data
+
+
 class ChoiceField(Field):
     widget = Select
     default_error_messages = {
@@ -739,6 +791,7 @@ class TypedChoiceField(ChoiceField):
     def validate(self, value):
         pass
 
+
 class MultipleChoiceField(ChoiceField):
     hidden_widget = MultipleHiddenInput
     widget = SelectMultiple
@@ -765,6 +818,18 @@ class MultipleChoiceField(ChoiceField):
             if not self.valid_value(val):
                 raise ValidationError(self.error_messages['invalid_choice'] % {'value': val})
 
+    def _has_changed(self, initial, data):
+        if initial is None:
+            initial = []
+        if data is None:
+            data = []
+        if len(initial) != len(data):
+            return True
+        initial_set = set([force_text(value) for value in initial])
+        data_set = set([force_text(value) for value in data])
+        return data_set != initial_set
+
+
 class TypedMultipleChoiceField(MultipleChoiceField):
     def __init__(self, *args, **kwargs):
         self.coerce = kwargs.pop('coerce', lambda val: val)
@@ -899,6 +964,18 @@ class MultiValueField(Field):
         """
         raise NotImplementedError('Subclasses must implement this method.')
 
+    def _has_changed(self, initial, data):
+        if initial is None:
+            initial = ['' for x in range(0, len(data))]
+        else:
+            if not isinstance(initial, list):
+                initial = self.widget.decompress(initial)
+        for field, initial, data in zip(self.fields, initial, data):
+            if field._has_changed(initial, data):
+                return True
+        return False
+
+
 class FilePathField(ChoiceField):
     def __init__(self, path, match=None, recursive=False, allow_files=True,
                  allow_folders=False, required=True, widget=None, label=None,
diff --git a/django/forms/forms.py b/django/forms/forms.py
index 3299c2becc..f532391296 100644
--- a/django/forms/forms.py
+++ b/django/forms/forms.py
@@ -341,7 +341,13 @@ class BaseForm(object):
                     hidden_widget = field.hidden_widget()
                     initial_value = hidden_widget.value_from_datadict(
                         self.data, self.files, initial_prefixed_name)
-                if field.widget._has_changed(initial_value, data_value):
+                if hasattr(field.widget, '_has_changed'):
+                    warnings.warn("The _has_changed method on widgets is deprecated,"
+                        " define it at field level instead.",
+                        PendingDeprecationWarning, stacklevel=2)
+                    if field.widget._has_changed(initial_value, data_value):
+                        self._changed_data.append(name)
+                elif field._has_changed(initial_value, data_value):
                     self._changed_data.append(name)
         return self._changed_data
     changed_data = property(_get_changed_data)
diff --git a/django/forms/models.py b/django/forms/models.py
index 03a14dc9ff..837da74814 100644
--- a/django/forms/models.py
+++ b/django/forms/models.py
@@ -858,15 +858,12 @@ def inlineformset_factory(parent_model, model, form=ModelForm,
 
 # Fields #####################################################################
 
-class InlineForeignKeyHiddenInput(HiddenInput):
-    def _has_changed(self, initial, data):
-        return False
-
 class InlineForeignKeyField(Field):
     """
     A basic integer field that deals with validating the given value to a
     given parent instance in an inline.
     """
+    widget = HiddenInput
     default_error_messages = {
         'invalid_choice': _('The inline foreign key did not match the parent instance primary key.'),
     }
@@ -881,7 +878,6 @@ class InlineForeignKeyField(Field):
             else:
                 kwargs["initial"] = self.parent_instance.pk
         kwargs["required"] = False
-        kwargs["widget"] = InlineForeignKeyHiddenInput
         super(InlineForeignKeyField, self).__init__(*args, **kwargs)
 
     def clean(self, value):
@@ -899,6 +895,9 @@ class InlineForeignKeyField(Field):
             raise ValidationError(self.error_messages['invalid_choice'])
         return self.parent_instance
 
+    def _has_changed(self, initial, data):
+        return False
+
 class ModelChoiceIterator(object):
     def __init__(self, field):
         self.field = field
diff --git a/django/forms/widgets.py b/django/forms/widgets.py
index d6ea56f0c8..303844d44b 100644
--- a/django/forms/widgets.py
+++ b/django/forms/widgets.py
@@ -208,25 +208,6 @@ class Widget(six.with_metaclass(MediaDefiningClass)):
         """
         return data.get(name, None)
 
-    def _has_changed(self, initial, data):
-        """
-        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 inital value we get
-        # is None, replace it w/ ''.
-        if data is None:
-            data_value = ''
-        else:
-            data_value = data
-        if initial is None:
-            initial_value = ''
-        else:
-            initial_value = initial
-        if force_text(initial_value) != force_text(data_value):
-            return True
-        return False
-
     def id_for_label(self, id_):
         """
         Returns the HTML ID attribute of this Widget for use by a <label>,
@@ -325,10 +306,6 @@ class FileInput(Input):
         "File widgets take data from FILES, not POST"
         return files.get(name, None)
 
-    def _has_changed(self, initial, data):
-        if data is None:
-            return False
-        return True
 
 FILE_INPUT_CONTRADICTION = object()
 
@@ -426,17 +403,6 @@ class DateInput(TextInput):
             return value.strftime(self.format)
         return value
 
-    def _has_changed(self, initial, data):
-        # If our field has show_hidden_initial=True, initial will be a string
-        # formatted by HiddenInput using formats.localize_input, which is not
-        # necessarily the format used for this widget. Attempt to convert it.
-        try:
-            input_format = formats.get_format('DATE_INPUT_FORMATS')[0]
-            initial = datetime.datetime.strptime(initial, input_format).date()
-        except (TypeError, ValueError):
-            pass
-        return super(DateInput, self)._has_changed(self._format_value(initial), data)
-
 
 class DateTimeInput(TextInput):
     def __init__(self, attrs=None, format=None):
@@ -456,17 +422,6 @@ class DateTimeInput(TextInput):
             return value.strftime(self.format)
         return value
 
-    def _has_changed(self, initial, data):
-        # If our field has show_hidden_initial=True, initial will be a string
-        # formatted by HiddenInput using formats.localize_input, which is not
-        # necessarily the format used for this widget. Attempt to convert it.
-        try:
-            input_format = formats.get_format('DATETIME_INPUT_FORMATS')[0]
-            initial = datetime.datetime.strptime(initial, input_format)
-        except (TypeError, ValueError):
-            pass
-        return super(DateTimeInput, self)._has_changed(self._format_value(initial), data)
-
 
 class TimeInput(TextInput):
     def __init__(self, attrs=None, format=None):
@@ -485,17 +440,6 @@ class TimeInput(TextInput):
             return value.strftime(self.format)
         return value
 
-    def _has_changed(self, initial, data):
-        # If our field has show_hidden_initial=True, initial will be a string
-        # formatted by HiddenInput using formats.localize_input, which is not
-        # necessarily the format used for this  widget. Attempt to convert it.
-        try:
-            input_format = formats.get_format('TIME_INPUT_FORMATS')[0]
-            initial = datetime.datetime.strptime(initial, input_format).time()
-        except (TypeError, ValueError):
-            pass
-        return super(TimeInput, self)._has_changed(self._format_value(initial), data)
-
 
 # Defined at module level so that CheckboxInput is picklable (#17976)
 def boolean_check(v):
@@ -530,13 +474,6 @@ class CheckboxInput(Widget):
             value = values.get(value.lower(), value)
         return bool(value)
 
-    def _has_changed(self, initial, data):
-        # Sometimes data or initial could be None or '' which should be the
-        # same thing as False.
-        if initial == 'False':
-            # show_hidden_initial may have transformed False to 'False'
-            initial = False
-        return bool(initial) != bool(data)
 
 class Select(Widget):
     allow_multiple_selected = False
@@ -612,14 +549,6 @@ class NullBooleanSelect(Select):
                 'False': False,
                 False: False}.get(value, None)
 
-    def _has_changed(self, initial, data):
-        # For a NullBooleanSelect, None (unknown) and False (No)
-        # are not the same
-        if initial is not None:
-            initial = bool(initial)
-        if data is not None:
-            data = bool(data)
-        return initial != data
 
 class SelectMultiple(Select):
     allow_multiple_selected = True
@@ -639,16 +568,6 @@ class SelectMultiple(Select):
             return data.getlist(name)
         return data.get(name, None)
 
-    def _has_changed(self, initial, data):
-        if initial is None:
-            initial = []
-        if data is None:
-            data = []
-        if len(initial) != len(data):
-            return True
-        initial_set = set([force_text(value) for value in initial])
-        data_set = set([force_text(value) for value in data])
-        return data_set != initial_set
 
 @python_2_unicode_compatible
 class RadioInput(SubWidget):
@@ -844,17 +763,6 @@ class MultiWidget(Widget):
     def value_from_datadict(self, data, files, name):
         return [widget.value_from_datadict(data, files, name + '_%s' % i) for i, widget in enumerate(self.widgets)]
 
-    def _has_changed(self, initial, data):
-        if initial is None:
-            initial = ['' for x in range(0, len(data))]
-        else:
-            if not isinstance(initial, list):
-                initial = self.decompress(initial)
-        for widget, initial, data in zip(self.widgets, initial, data):
-            if widget._has_changed(initial, data):
-                return True
-        return False
-
     def format_output(self, rendered_widgets):
         """
         Given a list of rendered widgets (as strings), returns a Unicode string
diff --git a/docs/releases/1.6.txt b/docs/releases/1.6.txt
index 89d7bb3c05..29ecad3e9f 100644
--- a/docs/releases/1.6.txt
+++ b/docs/releases/1.6.txt
@@ -67,3 +67,9 @@ If you're relying on this feature, you should add
 ``'django.middleware.common.BrokenLinkEmailsMiddleware'`` to your
 :setting:`MIDDLEWARE_CLASSES` setting and remove ``SEND_BROKEN_LINK_EMAILS``
 from your settings.
+
+``_has_changed`` method on widgets
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+If you defined your own form widgets and defined the ``_has_changed`` method
+on a widget, you should now define this method on the form field itself.
diff --git a/tests/regressiontests/admin_widgets/tests.py b/tests/regressiontests/admin_widgets/tests.py
index 76aa9f448f..452387078d 100644
--- a/tests/regressiontests/admin_widgets/tests.py
+++ b/tests/regressiontests/admin_widgets/tests.py
@@ -425,13 +425,6 @@ class ManyToManyRawIdWidgetTest(DjangoTestCase):
             '<input type="text" name="test" value="%(m1pk)s" class="vManyToManyRawIdAdminField" /><a href="/widget_admin/admin_widgets/member/" class="related-lookup" id="lookup_id_test" onclick="return showRelatedObjectLookupPopup(this);"> <img src="%(ADMIN_STATIC_PREFIX)simg/selector-search.gif" width="16" height="16" alt="Lookup" /></a>' % dict(admin_static_prefix(), m1pk=m1.pk)
         )
 
-        self.assertEqual(w._has_changed(None, None), False)
-        self.assertEqual(w._has_changed([], None), False)
-        self.assertEqual(w._has_changed(None, ['1']), True)
-        self.assertEqual(w._has_changed([1, 2], ['1', '2']), False)
-        self.assertEqual(w._has_changed([1, 2], ['1']), True)
-        self.assertEqual(w._has_changed([1, 2], ['1', '3']), True)
-
     def test_m2m_related_model_not_in_admin(self):
         # M2M relationship with model not registered with admin site. Raw ID
         # widget should have no magnifying glass link. See #16542
diff --git a/tests/regressiontests/forms/tests/extra.py b/tests/regressiontests/forms/tests/extra.py
index 07acb29741..762b774a93 100644
--- a/tests/regressiontests/forms/tests/extra.py
+++ b/tests/regressiontests/forms/tests/extra.py
@@ -428,6 +428,23 @@ class FormsExtraTestCase(TestCase, AssertFormErrorsMixin):
         # If insufficient data is provided, None is substituted
         self.assertFormErrors(['This field is required.'], f.clean, ['some text',['JP']])
 
+        # test with no initial data
+        self.assertTrue(f._has_changed(None, ['some text', ['J','P'], ['2007-04-25','6:24:00']]))
+
+        # test when the data is the same as initial
+        self.assertFalse(f._has_changed('some text,JP,2007-04-25 06:24:00',
+            ['some text', ['J','P'], ['2007-04-25','6:24:00']]))
+
+        # test when the first widget's data has changed
+        self.assertTrue(f._has_changed('some text,JP,2007-04-25 06:24:00',
+            ['other text', ['J','P'], ['2007-04-25','6:24:00']]))
+
+        # test when the last widget's data has changed. this ensures that it is not
+        # short circuiting while testing the widgets.
+        self.assertTrue(f._has_changed('some text,JP,2007-04-25 06:24:00',
+            ['some text', ['J','P'], ['2009-04-25','11:44:00']]))
+
+
         class ComplexFieldForm(Form):
             field1 = ComplexField(widget=w)
 
@@ -725,8 +742,8 @@ class FormsExtraL10NTestCase(TestCase):
 
     def test_l10n_date_changed(self):
         """
-        Ensure that SelectDateWidget._has_changed() works correctly with a
-        localized date format.
+        Ensure that DateField._has_changed() with SelectDateWidget works
+        correctly with a localized date format.
         Refs #17165.
         """
         # With Field.show_hidden_initial=False -----------------------
diff --git a/tests/regressiontests/forms/tests/fields.py b/tests/regressiontests/forms/tests/fields.py
index e17d976fcf..7deb345a33 100644
--- a/tests/regressiontests/forms/tests/fields.py
+++ b/tests/regressiontests/forms/tests/fields.py
@@ -35,6 +35,7 @@ from decimal import Decimal
 from django.core.files.uploadedfile import SimpleUploadedFile
 from django.forms import *
 from django.test import SimpleTestCase
+from django.utils import formats
 from django.utils import six
 from django.utils._os import upath
 
@@ -362,6 +363,13 @@ class FieldsTests(SimpleTestCase):
         f = DateField()
         self.assertRaisesMessage(ValidationError, "'Enter a valid date.'", f.clean, 'a\x00b')
 
+    def test_datefield_changed(self):
+        format = '%d/%m/%Y'
+        f = DateField(input_formats=[format])
+        d = datetime.date(2007, 9, 17)
+        self.assertFalse(f._has_changed(d, '17/09/2007'))
+        self.assertFalse(f._has_changed(d.strftime(format), '17/09/2007'))
+
     # TimeField ###################################################################
 
     def test_timefield_1(self):
@@ -388,6 +396,18 @@ class FieldsTests(SimpleTestCase):
         self.assertEqual(datetime.time(14, 25, 59), f.clean(' 14:25:59 '))
         self.assertRaisesMessage(ValidationError, "'Enter a valid time.'", f.clean, '   ')
 
+    def test_timefield_changed(self):
+        t1 = datetime.time(12, 51, 34, 482548)
+        t2 = datetime.time(12, 51)
+        format = '%H:%M'
+        f = TimeField(input_formats=[format])
+        self.assertTrue(f._has_changed(t1, '12:51'))
+        self.assertFalse(f._has_changed(t2, '12:51'))
+
+        format = '%I:%M %p'
+        f = TimeField(input_formats=[format])
+        self.assertFalse(f._has_changed(t2.strftime(format), '12:51 PM'))
+
     # DateTimeField ###############################################################
 
     def test_datetimefield_1(self):
@@ -446,6 +466,15 @@ class FieldsTests(SimpleTestCase):
     def test_datetimefield_5(self):
         f = DateTimeField(input_formats=['%Y.%m.%d %H:%M:%S.%f'])
         self.assertEqual(datetime.datetime(2006, 10, 25, 14, 30, 45, 200), f.clean('2006.10.25 14:30:45.0002'))
+
+    def test_datetimefield_changed(self):
+        format = '%Y %m %d %I:%M %p'
+        f = DateTimeField(input_formats=[format])
+        d = datetime.datetime(2006, 9, 17, 14, 30, 0)
+        self.assertFalse(f._has_changed(d, '2006 09 17 2:30 PM'))
+        # Initial value may be a string from a hidden input
+        self.assertFalse(f._has_changed(d.strftime(format), '2006 09 17 2:30 PM'))
+
     # RegexField ##################################################################
 
     def test_regexfield_1(self):
@@ -566,6 +595,29 @@ class FieldsTests(SimpleTestCase):
         self.assertEqual(SimpleUploadedFile,
                          type(f.clean(SimpleUploadedFile('name', b''))))
 
+    def test_filefield_changed(self):
+        '''
+        Test for the behavior of _has_changed for FileField. The value of data will
+        more than likely come from request.FILES. The value of initial data will
+        likely be a filename stored in the database. Since its value is of no use to
+        a FileField it is ignored.
+        '''
+        f = FileField()
+
+        # No file was uploaded and no initial data.
+        self.assertFalse(f._has_changed('', None))
+
+        # A file was uploaded and no initial data.
+        self.assertTrue(f._has_changed('', {'filename': 'resume.txt', 'content': 'My resume'}))
+
+        # A file was not uploaded, but there is initial data
+        self.assertFalse(f._has_changed('resume.txt', None))
+
+        # A file was uploaded and there is initial data (file identity is not dealt
+        # with here)
+        self.assertTrue(f._has_changed('resume.txt', {'filename': 'resume.txt', 'content': 'My resume'}))
+
+
     # URLField ##################################################################
 
     def test_urlfield_1(self):
@@ -709,6 +761,18 @@ class FieldsTests(SimpleTestCase):
     def test_boolean_picklable(self):
         self.assertIsInstance(pickle.loads(pickle.dumps(BooleanField())), BooleanField)
 
+    def test_booleanfield_changed(self):
+        f = BooleanField()
+        self.assertFalse(f._has_changed(None, None))
+        self.assertFalse(f._has_changed(None, ''))
+        self.assertFalse(f._has_changed('', None))
+        self.assertFalse(f._has_changed('', ''))
+        self.assertTrue(f._has_changed(False, 'on'))
+        self.assertFalse(f._has_changed(True, 'on'))
+        self.assertTrue(f._has_changed(True, ''))
+        # Initial value may have mutated to a string due to show_hidden_initial (#19537)
+        self.assertTrue(f._has_changed('False', 'on'))
+
     # ChoiceField #################################################################
 
     def test_choicefield_1(self):
@@ -825,6 +889,16 @@ class FieldsTests(SimpleTestCase):
         self.assertEqual(False, f.cleaned_data['nullbool1'])
         self.assertEqual(None, f.cleaned_data['nullbool2'])
 
+    def test_nullbooleanfield_changed(self):
+        f = NullBooleanField()
+        self.assertTrue(f._has_changed(False, None))
+        self.assertTrue(f._has_changed(None, False))
+        self.assertFalse(f._has_changed(None, None))
+        self.assertFalse(f._has_changed(False, False))
+        self.assertTrue(f._has_changed(True, False))
+        self.assertTrue(f._has_changed(True, None))
+        self.assertTrue(f._has_changed(True, False))
+
     # MultipleChoiceField #########################################################
 
     def test_multiplechoicefield_1(self):
@@ -866,6 +940,16 @@ class FieldsTests(SimpleTestCase):
         self.assertRaisesMessage(ValidationError, "'Select a valid choice. 6 is not one of the available choices.'", f.clean, ['6'])
         self.assertRaisesMessage(ValidationError, "'Select a valid choice. 6 is not one of the available choices.'", f.clean, ['1','6'])
 
+    def test_multiplechoicefield_changed(self):
+        f = MultipleChoiceField(choices=[('1', 'One'), ('2', 'Two'), ('3', 'Three')])
+        self.assertFalse(f._has_changed(None, None))
+        self.assertFalse(f._has_changed([], None))
+        self.assertTrue(f._has_changed(None, ['1']))
+        self.assertFalse(f._has_changed([1, 2], ['1', '2']))
+        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']))
+
     # TypedMultipleChoiceField ############################################################
     # TypedMultipleChoiceField is just like MultipleChoiceField, except that coerced types
     # will be returned:
@@ -1048,3 +1132,9 @@ class FieldsTests(SimpleTestCase):
         self.assertRaisesMessage(ValidationError, "'Enter a valid time.'", f.clean, ['2006-01-10', ''])
         self.assertRaisesMessage(ValidationError, "'Enter a valid time.'", f.clean, ['2006-01-10'])
         self.assertRaisesMessage(ValidationError, "'Enter a valid date.'", f.clean, ['', '07:30'])
+
+    def test_splitdatetimefield_changed(self):
+        f = SplitDateTimeField(input_date_formats=['%d/%m/%Y'])
+        self.assertTrue(f._has_changed(datetime.datetime(2008, 5, 6, 12, 40, 00), ['2008-05-06', '12:40:00']))
+        self.assertFalse(f._has_changed(datetime.datetime(2008, 5, 6, 12, 40, 00), ['06/05/2008', '12:40']))
+        self.assertTrue(f._has_changed(datetime.datetime(2008, 5, 6, 12, 40, 00), ['06/05/2008', '12:41']))
diff --git a/tests/regressiontests/forms/tests/widgets.py b/tests/regressiontests/forms/tests/widgets.py
index 7a2961358a..6aa56ec8b0 100644
--- a/tests/regressiontests/forms/tests/widgets.py
+++ b/tests/regressiontests/forms/tests/widgets.py
@@ -148,25 +148,6 @@ class FormsWidgetTestCase(TestCase):
 
         self.assertHTMLEqual(w.render('email', 'ŠĐĆŽćžšđ', attrs={'class': 'fun'}), '<input type="file" class="fun" name="email" />')
 
-        # Test for the behavior of _has_changed for FileInput. The value of data will
-        # more than likely come from request.FILES. The value of initial data will
-        # likely be a filename stored in the database. Since its value is of no use to
-        # a FileInput it is ignored.
-        w = FileInput()
-
-        # No file was uploaded and no initial data.
-        self.assertFalse(w._has_changed('', None))
-
-        # A file was uploaded and no initial data.
-        self.assertTrue(w._has_changed('', {'filename': 'resume.txt', 'content': 'My resume'}))
-
-        # A file was not uploaded, but there is initial data
-        self.assertFalse(w._has_changed('resume.txt', None))
-
-        # A file was uploaded and there is initial data (file identity is not dealt
-        # with here)
-        self.assertTrue(w._has_changed('resume.txt', {'filename': 'resume.txt', 'content': 'My resume'}))
-
     def test_textarea(self):
         w = Textarea()
         self.assertHTMLEqual(w.render('msg', ''), '<textarea rows="10" cols="40" name="msg"></textarea>')
@@ -233,16 +214,6 @@ class FormsWidgetTestCase(TestCase):
         self.assertIsInstance(value, bool)
         self.assertTrue(value)
 
-        self.assertFalse(w._has_changed(None, None))
-        self.assertFalse(w._has_changed(None, ''))
-        self.assertFalse(w._has_changed('', None))
-        self.assertFalse(w._has_changed('', ''))
-        self.assertTrue(w._has_changed(False, 'on'))
-        self.assertFalse(w._has_changed(True, 'on'))
-        self.assertTrue(w._has_changed(True, ''))
-        # Initial value may have mutated to a string due to show_hidden_initial (#19537)
-        self.assertTrue(w._has_changed('False', 'on'))
-
     def test_select(self):
         w = Select()
         self.assertHTMLEqual(w.render('beatle', 'J', choices=(('J', 'John'), ('P', 'Paul'), ('G', 'George'), ('R', 'Ringo'))), """<select name="beatle">
@@ -415,13 +386,6 @@ class FormsWidgetTestCase(TestCase):
 <option value="2">Yes</option>
 <option value="3" selected="selected">No</option>
 </select>""")
-        self.assertTrue(w._has_changed(False, None))
-        self.assertTrue(w._has_changed(None, False))
-        self.assertFalse(w._has_changed(None, None))
-        self.assertFalse(w._has_changed(False, False))
-        self.assertTrue(w._has_changed(True, False))
-        self.assertTrue(w._has_changed(True, None))
-        self.assertTrue(w._has_changed(True, False))
 
     def test_selectmultiple(self):
         w = SelectMultiple()
@@ -535,14 +499,6 @@ class FormsWidgetTestCase(TestCase):
         # Unicode choices are correctly rendered as HTML
         self.assertHTMLEqual(w.render('nums', ['ŠĐĆŽćžšđ'], choices=[('ŠĐĆŽćžšđ', 'ŠĐabcĆŽćžšđ'), ('ćžšđ', 'abcćžšđ')]), '<select multiple="multiple" name="nums">\n<option value="1">1</option>\n<option value="2">2</option>\n<option value="3">3</option>\n<option value="\u0160\u0110\u0106\u017d\u0107\u017e\u0161\u0111" selected="selected">\u0160\u0110abc\u0106\u017d\u0107\u017e\u0161\u0111</option>\n<option value="\u0107\u017e\u0161\u0111">abc\u0107\u017e\u0161\u0111</option>\n</select>')
 
-        # Test the usage of _has_changed
-        self.assertFalse(w._has_changed(None, None))
-        self.assertFalse(w._has_changed([], None))
-        self.assertTrue(w._has_changed(None, ['1']))
-        self.assertFalse(w._has_changed([1, 2], ['1', '2']))
-        self.assertTrue(w._has_changed([1, 2], ['1']))
-        self.assertTrue(w._has_changed([1, 2], ['1', '3']))
-
         # Choices can be nested one level in order to create HTML optgroups:
         w.choices = (('outer1', 'Outer 1'), ('Group "1"', (('inner1', 'Inner 1'), ('inner2', 'Inner 2'))))
         self.assertHTMLEqual(w.render('nestchoice', None), """<select multiple="multiple" name="nestchoice">
@@ -844,15 +800,6 @@ beatle J R Ringo False""")
 <li><label><input type="checkbox" name="escape" value="good" /> you &gt; me</label></li>
 </ul>""")
 
-        # Test the usage of _has_changed
-        self.assertFalse(w._has_changed(None, None))
-        self.assertFalse(w._has_changed([], None))
-        self.assertTrue(w._has_changed(None, ['1']))
-        self.assertFalse(w._has_changed([1, 2], ['1', '2']))
-        self.assertTrue(w._has_changed([1, 2], ['1']))
-        self.assertTrue(w._has_changed([1, 2], ['1', '3']))
-        self.assertFalse(w._has_changed([2, 1], ['1', '2']))
-
         # Unicode choices are correctly rendered as HTML
         self.assertHTMLEqual(w.render('nums', ['ŠĐĆŽćžšđ'], choices=[('ŠĐĆŽćžšđ', 'ŠĐabcĆŽćžšđ'), ('ćžšđ', 'abcćžšđ')]), '<ul>\n<li><label><input type="checkbox" name="nums" value="1" /> 1</label></li>\n<li><label><input type="checkbox" name="nums" value="2" /> 2</label></li>\n<li><label><input type="checkbox" name="nums" value="3" /> 3</label></li>\n<li><label><input checked="checked" type="checkbox" name="nums" value="\u0160\u0110\u0106\u017d\u0107\u017e\u0161\u0111" /> \u0160\u0110abc\u0106\u017d\u0107\u017e\u0161\u0111</label></li>\n<li><label><input type="checkbox" name="nums" value="\u0107\u017e\u0161\u0111" /> abc\u0107\u017e\u0161\u0111</label></li>\n</ul>')
 
@@ -886,21 +833,6 @@ beatle J R Ringo False""")
         w = MyMultiWidget(widgets=(TextInput(attrs={'class': 'big'}), TextInput(attrs={'class': 'small'})), attrs={'id': 'bar'})
         self.assertHTMLEqual(w.render('name', ['john', 'lennon']), '<input id="bar_0" type="text" class="big" value="john" name="name_0" /><br /><input id="bar_1" type="text" class="small" value="lennon" name="name_1" />')
 
-        w = MyMultiWidget(widgets=(TextInput(), TextInput()))
-
-        # test with no initial data
-        self.assertTrue(w._has_changed(None, ['john', 'lennon']))
-
-        # test when the data is the same as initial
-        self.assertFalse(w._has_changed('john__lennon', ['john', 'lennon']))
-
-        # test when the first widget's data has changed
-        self.assertTrue(w._has_changed('john__lennon', ['alfred', 'lennon']))
-
-        # test when the last widget's data has changed. this ensures that it is not
-        # short circuiting while testing the widgets.
-        self.assertTrue(w._has_changed('john__lennon', ['john', 'denver']))
-
     def test_splitdatetime(self):
         w = SplitDateTimeWidget()
         self.assertHTMLEqual(w.render('date', ''), '<input type="text" name="date_0" /><input type="text" name="date_1" />')
@@ -916,10 +848,6 @@ beatle J R Ringo False""")
         w = SplitDateTimeWidget(date_format='%d/%m/%Y', time_format='%H:%M')
         self.assertHTMLEqual(w.render('date', datetime.datetime(2006, 1, 10, 7, 30)), '<input type="text" name="date_0" value="10/01/2006" /><input type="text" name="date_1" value="07:30" />')
 
-        self.assertTrue(w._has_changed(datetime.datetime(2008, 5, 6, 12, 40, 00), ['2008-05-06', '12:40:00']))
-        self.assertFalse(w._has_changed(datetime.datetime(2008, 5, 6, 12, 40, 00), ['06/05/2008', '12:40']))
-        self.assertTrue(w._has_changed(datetime.datetime(2008, 5, 6, 12, 40, 00), ['06/05/2008', '12:41']))
-
     def test_datetimeinput(self):
         w = DateTimeInput()
         self.assertHTMLEqual(w.render('date', None), '<input type="text" name="date" />')
@@ -934,13 +862,6 @@ beatle J R Ringo False""")
         # Use 'format' to change the way a value is displayed.
         w = DateTimeInput(format='%d/%m/%Y %H:%M', attrs={'type': 'datetime'})
         self.assertHTMLEqual(w.render('date', d), '<input type="datetime" name="date" value="17/09/2007 12:51" />')
-        self.assertFalse(w._has_changed(d, '17/09/2007 12:51'))
-
-        # Make sure a custom format works with _has_changed. The hidden input will use
-        data = datetime.datetime(2010, 3, 6, 12, 0, 0)
-        custom_format = '%d.%m.%Y %H:%M'
-        w = DateTimeInput(format=custom_format)
-        self.assertFalse(w._has_changed(formats.localize_input(data), data.strftime(custom_format)))
 
     def test_dateinput(self):
         w = DateInput()
@@ -957,13 +878,6 @@ beatle J R Ringo False""")
         # Use 'format' to change the way a value is displayed.
         w = DateInput(format='%d/%m/%Y', attrs={'type': 'date'})
         self.assertHTMLEqual(w.render('date', d), '<input type="date" name="date" value="17/09/2007" />')
-        self.assertFalse(w._has_changed(d, '17/09/2007'))
-
-        # Make sure a custom format works with _has_changed. The hidden input will use
-        data = datetime.date(2010, 3, 6)
-        custom_format = '%d.%m.%Y'
-        w = DateInput(format=custom_format)
-        self.assertFalse(w._has_changed(formats.localize_input(data), data.strftime(custom_format)))
 
     def test_timeinput(self):
         w = TimeInput()
@@ -982,13 +896,6 @@ beatle J R Ringo False""")
         # Use 'format' to change the way a value is displayed.
         w = TimeInput(format='%H:%M', attrs={'type': 'time'})
         self.assertHTMLEqual(w.render('time', t), '<input type="time" name="time" value="12:51" />')
-        self.assertFalse(w._has_changed(t, '12:51'))
-
-        # Make sure a custom format works with _has_changed. The hidden input will use
-        data = datetime.time(13, 0)
-        custom_format = '%I:%M %p'
-        w = TimeInput(format=custom_format)
-        self.assertFalse(w._has_changed(formats.localize_input(data), data.strftime(custom_format)))
 
     def test_splithiddendatetime(self):
         from django.forms.widgets import SplitHiddenDateTimeWidget
@@ -1016,10 +923,6 @@ class FormsI18NWidgetsTestCase(TestCase):
         deactivate()
         super(FormsI18NWidgetsTestCase, self).tearDown()
 
-    def test_splitdatetime(self):
-        w = SplitDateTimeWidget(date_format='%d/%m/%Y', time_format='%H:%M')
-        self.assertTrue(w._has_changed(datetime.datetime(2008, 5, 6, 12, 40, 00), ['06.05.2008', '12:41']))
-
     def test_datetimeinput(self):
         w = DateTimeInput()
         d = datetime.datetime(2007, 9, 17, 12, 51, 34, 482548)