private function _get_id(string $request, $params): ?string
  {
    if ( $this->check() ){
      if ( $params ){
        return $this->db->select_one('bbn_observers', 'id', [
          'id_string' => $this->_get_id_string($request, $params)
        ]);
      }
      return $this->db->get_one("
        SELECT id
        FROM bbn_observers
        WHERE `request` LIKE ?
        AND `params` IS NULL
        AND `public` = 1",
        $request);
    }
    return null;
  }