Make ChoiceField.from_native() follow IntegerField behaviour on empty values

rest_framework/fields.py

@@ -514,6 +514,11 @@ class ChoiceField(WritableField):
                     return True
         return False
 
+    def from_native(self, value):
+        if value in validators.EMPTY_VALUES:
+            return None
+        return super(ChoiceField, self).from_native(value)
+
 
 class EmailField(CharField):
     type_name = 'EmailField'

rest_framework/tests/test_fields.py

@@ -688,6 +688,14 @@ class ChoiceFieldTests(TestCase):
         f = serializers.ChoiceField(required=False, choices=self.SAMPLE_CHOICES)
         self.assertEqual(f.choices, models.fields.BLANK_CHOICE_DASH + self.SAMPLE_CHOICES)
 
+    def test_from_native_empty(self):
+        """
+        Make sure from_native() returns None on empty param.
+        """
+        f = serializers.ChoiceField(choices=self.SAMPLE_CHOICES)
+        result = f.from_native('')
+        self.assertEqual(result, None)
+
 
 class EmailFieldTests(TestCase):
     """