protected function getNodeValueAsObject($xquery, $className)
    {
      $nodeList = $this->document->getXPath()->query($xquery, $this->node);

      if($nodeList->length == 0)
        throw new Exception(__METHOD__ . '; ' . $xquery . ' node is missing');

      return new $className(utf8_decode($nodeList->item(0)->nodeValue));
    }