无法获取<p>数据</p>

Question

我有一个包含此类信息的源文件

<div itemprop="comment" itemscope itemtype="http://schema.org/UserComments" class="comment_item" id="comment_60857544">
<meta itemprop="discusses" content="http://source.com/permalink/comments/60857544" />
<a id="c60857544"></a>
<p>
    <div class="pp-container">
        <img class="gravatar" src="http://static.source.com/sharedDocs/images/frontend/default_pp.png" />
    </div>
    a comment is available here
</p>
<div class="itemfooter">comment information
</div>

代码

  $comment_id = $xpath->query("a[@id]", $commentNode)->item(0)->getAttribute('id');

正确检索评论ID 但评论内容检索不起作用

$tmpdom = new DomDocument();
  if ($titleNode = $xpath->query('h3', $commentNode)->item(0))
  {
    $tmpnode = $tmpdom->createElement('p');
    $tmpnode->appendChild($tmpdom->createElement('strong', esc_html($titleNode->textContent)));
    $tmpdom->appendChild($tmpnode);
  }

  foreach ($xpath->query('//p', $commentNode) as $comment_p)
  {
    $tmpdom->appendChild($tmpdom->importNode($comment_p, true));
  }

  $data['comment_content'] = trim(preg_replace('#<p>[\s]*</p>#U', '', $tmpdom->saveHTML()));

有什么想法吗？