          self._data = None
          self._files = None
          self._errors = None
  
      #####
      # Methods to determine which fields to use when (de)serializing objects.
  
 
</s> remove         if self.parent.object:
            # Set the serializer object if it exists
            obj = getattr(self.parent.object, field_name)
            self.object = obj
 </s> add         # Set the serializer object if it exists
        obj = getattr(self.parent.object, field_name) if self.parent.object else None </s> remove             into[(self.source or field_name)] = None
 </s> add             if isinstance(self, ModelSerializer):
                self._delete = True
                self.object = obj
                into[(self.source or field_name)] = self
            else:
                into[(self.source or field_name)] = None </s> remove                 self.object = serializer.object
                into[self.source or field_name] = serializer.object
 </s> add                 if isinstance(serializer, ModelSerializer):
                    into[self.source or field_name] = serializer
                else:
                    into[self.source or field_name] = serializer.object </s> remove         self.messages = message
 </s> add         if isinstance(message, dict):
            self.messages = [message]
        else:
            self.messages = message
        self._delete = False
          self._data = None
          self._files = None
          self._errors = None
        self._delete = False
  
      #####
      # Methods to determine which fields to use when (de)serializing objects.
  
keep keep add keep keep keep keep
 One-to-one writable, nested serializer support 
rest_framework/serializers.py