code: def query_topology_db(self, dict_convert=False, **req):
          
          session = db.get_session()
          with session.begin(subtransactions=True):
              try:
                  # Check if entry exists.
                  topo_disc = session.query(DfaTopologyDb).filter_by(**req).all()
              except orm_exc.NoResultFound:
                  LOG.info("No Topology results found for %s", req)
                  return None
          if dict_convert:
              return self._convert_topo_obj_dict(topo_disc)
          return topo_disc
docs: Query an entry to the topology DB.