docs: def showcolumns(self, datastore_id=None, datasource_id=None):
          """ GET /datastores/{datastore_id}/datasources/{datasource_id}/columns: Get a
              specific datasource's columns within a given datastore. """
          datastore = self._get_datastore_by_id(datastore_id)
          if datastore is None:
              abort(404)
          discovery_result = discover_datasource_columns(datastore.ogrstring, datasource_id)
          if discovery_result is None:
              abort(404)
          # prevent JSON Array Cross-site Exploits (XSRF/CSRF)
          return {"columns": discovery_result}