Fixed #20039 -- Fixed has_changed form detection for required TypedChoiceFields

Thanks Florian Apolloner for the report and the review.
Also fixes #19643.

django/forms/fields.py

@@ -778,14 +778,15 @@ class ChoiceField(Field):
 
     def valid_value(self, value):
         "Check to see if the provided value is a valid choice"
+        text_value = force_text(value)
         for k, v in self.choices:
             if isinstance(v, (list, tuple)):
                 # This is an optgroup, so look inside the group for options
                 for k2, v2 in v:
-                    if value == smart_text(k2):
+                    if value == k2 or text_value == force_text(k2):
                         return True
             else:
-                if value == smart_text(k):
+                if value == k or text_value == force_text(k):
                     return True
         return False
 
@@ -801,7 +802,6 @@ class TypedChoiceField(ChoiceField):
         right type.
         """
         value = super(TypedChoiceField, self).to_python(value)
-        super(TypedChoiceField, self).validate(value)
         if value == self.empty_value or value in self.empty_values:
             return self.empty_value
         try:
@@ -810,9 +810,6 @@ class TypedChoiceField(ChoiceField):
             raise ValidationError(self.error_messages['invalid_choice'] % {'value': value})
         return value
 
-    def validate(self, value):
-        pass
-
 
 class MultipleChoiceField(ChoiceField):
     hidden_widget = MultipleHiddenInput
@@ -864,7 +861,6 @@ class TypedMultipleChoiceField(MultipleChoiceField):
         right type.
         """
         value = super(TypedMultipleChoiceField, self).to_python(value)
-        super(TypedMultipleChoiceField, self).validate(value)
         if value == self.empty_value or value in self.empty_values:
             return self.empty_value
         new_value = []
@@ -876,7 +872,11 @@ class TypedMultipleChoiceField(MultipleChoiceField):
         return new_value
 
     def validate(self, value):
-        pass
+        if value != self.empty_value:
+            super(TypedMultipleChoiceField, self).validate(value)
+        elif self.required:
+            raise ValidationError(self.error_messages['required'])
+
 
 class ComboField(Field):
     """

tests/forms_tests/tests/fields.py

@@ -911,6 +911,11 @@ class FieldsTests(SimpleTestCase):
         f = TypedChoiceField(choices=[(1, "+1"), (-1, "-1")], coerce=int, required=False, empty_value=None)
         self.assertEqual(None, f.clean(''))
 
+    def test_typedchoicefield_has_changed(self):
+        # has_changed should not trigger required validation
+        f = TypedChoiceField(choices=[(1, "+1"), (-1, "-1")], coerce=int, required=True)
+        self.assertFalse(f._has_changed(None, ''))
+
     # NullBooleanField ############################################################
 
     def test_nullbooleanfield_1(self):
@@ -1060,6 +1065,11 @@ class FieldsTests(SimpleTestCase):
         f = TypedMultipleChoiceField(choices=[(1, "+1"), (-1, "-1")], coerce=int, required=False, empty_value=None)
         self.assertEqual(None, f.clean([]))
 
+    def test_typedmultiplechoicefield_has_changed(self):
+        # has_changed should not trigger required validation
+        f = TypedMultipleChoiceField(choices=[(1, "+1"), (-1, "-1")], coerce=int, required=True)
+        self.assertFalse(f._has_changed(None, ''))
+
    # ComboField ##################################################################
 
     def test_combofield_1(self):

tests/forms_tests/tests/regressions.py

@@ -61,10 +61,10 @@ class FormsRegressionsTestCase(TestCase):
         UNITS = ((b'\xd0\xbc\xd0\xb5\xd1\x81.', b'\xd0\xbc\xd0\xb5\xd1\x81.'),
                  (b'\xd1\x88\xd1\x82.', b'\xd1\x88\xd1\x82.'))
         f = ChoiceField(choices=UNITS)
-        self.assertEqual(f.clean('\u0448\u0442.'), '\u0448\u0442.')
         with warnings.catch_warnings():
             # Ignore UnicodeWarning
             warnings.simplefilter("ignore")
+            self.assertEqual(f.clean('\u0448\u0442.'), '\u0448\u0442.')
             self.assertEqual(f.clean(b'\xd1\x88\xd1\x82.'), '\u0448\u0442.')
 
         # Translated error messages used to be buggy.