private function _insert(string $id_option, array $cfg): int
  {
    $json = ($tmp = $this->get_cfg(false, $cfg)) ? json_encode($tmp) : NULL;
    return $this->db->insert($this->class_cfg['table'], [
      $this->fields['id_option'] => $id_option,
      $this->fields['num'] => $cfg[$this->fields['num']] ?? NULL,
      $this->fields['text'] => $cfg[$this->fields['text']] ?? NULL,
      $this->fields['id_link'] => $cfg[$this->fields['id_link']] ?? NULL,
      $this->fields['id_alias'] => $cfg[$this->fields['id_alias']] ?? NULL,
      $this->fields['id_user'] => $this->id_user,
      $this->fields['cfg'] => $json
    ]);
  }