code: def __json(self):
          
          if self.exclude_list is None:
              self.exclude_list = []
          fields = {}
          for key, item in vars(self).items():
              if hasattr(self, '_sa_instance_state'):
                  # load only deferred objects
                  if len(orm.attributes.instance_state(self).unloaded) > 0:
                      mapper = inspect(self)
                      for column in mapper.attrs:
                          column.key
                          column.value
              if str(key).startswith('_') or key in self.exclude_list:
                  continue
              fields[key] = item
          obj = Json.safe_object(fields)
          return str(obj)
docs: Using the exclude lists, convert fields to a string.