code: def _get_list_related_field(
          self, field, filter_rel_field, page=None, page_size=None
      ):
          
          ret = list()
          if isinstance(field, Related) or isinstance(field, RelatedList):
              datamodel = self.datamodel.get_related_interface(field.name)
              filters = datamodel.get_filters(datamodel.get_search_columns_list())
              page, page_size = self._sanitize_page_args(page, page_size)
              order_field = self.order_rel_fields.get(field.name)
              if order_field:
                  order_column, order_direction = order_field
              else:
                  order_column, order_direction = "", ""
              if filter_rel_field:
                  filters = filters.add_filter_list(filter_rel_field)
              count, values = datamodel.query(
                  filters, order_column, order_direction, page=page, page_size=page_size
              )
              for value in values:
                  ret.append({"id": datamodel.get_pk_value(value), "value": str(value)})
          return count, ret
docs: Return a list of values for a related field
  
          :param field: Marshmallow field
          :param filter_rel_field: Filters for the related field
          :param page: The page index
          :param page_size: The page size
          :return: (int, list) total record count and list of dict with id and value