          if model_field:
              self.model_field = model_field
  
      def validate(self, value):
          pass
          # if value in validators.EMPTY_VALUES and self.required:
          #     raise ValidationError(self.error_messages['required'])
  
      def run_validators(self, value):
          if value in validators.EMPTY_VALUES:
              return
          errors = []
 
</s> remove             self._data = self.to_native(self.instance)
 </s> add             self._data = self.to_native(self.object) </s> remove         print match.group(1)
 </s> add  </s> remove             return self.restore_object(attrs, instance=getattr(self, 'instance', None))
 </s> add             return self.restore_object(attrs, instance=getattr(self, 'object', None)) </s> remove         self.instance = instance
 </s> add         self.object = instance </s> remove         self.required = not(readonly)
 </s> add         if required is None:
            self.required = not(readonly)
        else:
            assert not readonly, "Cannot set required=True and readonly=True"
            self.required = required
        if value in validators.EMPTY_VALUES and self.required:
            raise ValidationError(self.error_messages['required'])
          if model_field:
              self.model_field = model_field
  
      def validate(self, value):
        if value in validators.EMPTY_VALUES and self.required:
            raise ValidationError(self.error_messages['required'])
        if value in validators.EMPTY_VALUES and self.required:
            raise ValidationError(self.error_messages['required'])
        if value in validators.EMPTY_VALUES and self.required:
            raise ValidationError(self.error_messages['required'])
  
      def run_validators(self, value):
          if value in validators.EMPTY_VALUES:
              return
          errors = []
keep keep keep keep replace replace replace keep keep keep keep keep
 Fix some bits of serialization 
rest_framework/fields.py