updated timefield also

rest_framework/fields.py

@@ -1186,6 +1186,9 @@ class TimeField(Field):
         self.fail('invalid', format=humanized_format)
 
     def to_representation(self, value):
+        if not value:
+            return None
+
         output_format = getattr(self, 'format', api_settings.TIME_FORMAT)
 
         if output_format is None:

tests/test_fields.py

@@ -1030,7 +1030,9 @@ class TestTimeField(FieldValues):
         '99:99': ['Time has wrong format. Use one of these formats instead: hh:mm[:ss[.uuuuuu]].'],
     }
     outputs = {
-        datetime.time(13, 00): '13:00:00'
+        datetime.time(13, 00): '13:00:00',
+        None: None,
+        '': None,
     }
     field = serializers.TimeField()