          return exclusions
  
      def restore_object(self, attrs, instance=None):
          """
          Restore the model instance.
          """
 
</s> remove         try:
            instance.full_clean(exclude=self.get_validation_exclusions())
        except ValidationError, err:
            self._errors = err.message_dict
            return None

 </s> add 
    def full_clean(self, instance):
        """
        Perform Django's full_clean, and populate the `errors` dictionary
        if any validation errors occur.

        Note that we don't perform this inside the `.restore_object()` method,
        so that subclasses can override `.restore_object()`, and still get
        the full_clean validation checking.
        """
        try:
            instance.full_clean(exclude=self.get_validation_exclusions())
        except ValidationError, err:
            self._errors = err.message_dict
            return None
        return instance

          return exclusions
  
    def full_clean(self, instance):
        """
        Perform Django's full_clean, and populate the `errors` dictionary
        if any validation errors occur.

        Note that we don't perform this inside the `.restore_object()` method,
        so that subclasses can override `.restore_object()`, and still get
        the full_clean validation checking.
        """
        try:
            instance.full_clean(exclude=self.get_validation_exclusions())
        except ValidationError, err:
            self._errors = err.message_dict
            return None
        return instance

      def restore_object(self, attrs, instance=None):
          """
          Restore the model instance.
          """
keep add keep keep keep keep
 Ensure model field validation is performed for ModelSerializers with a custom restore_object method.  Fixes #623. 
rest_framework/serializers.py