<p>I'm translating my C# code for YouTube video comments into PHP. In order to properly nest comment replies, I need to re-arrange XML nodes. In PHP I'm using DOMDocument and DOMXPath which closely corresponds to C# XmlDocument. I've gotten pretty far in my translation but now I'm stuck on getting the parent node of a DOMElement. A DOMElement does not have a parent_node() property, only a DOMNode provides that property.</p>

<p>After determining that a comment is a reply to a previous comment based in the string "in-reply-to" in a link element, I need to get its parent node in order to nest it beneath the comment it is in reply to:</p>

<pre><code>// Get the parent entry node of this link element
$importnode = $objReplyXML-&gt;importNode($link-&gt;parent_node(), true);
</code></pre>

DOMElement
is a subclass of
DOMNode
, so it does have parent_node property. Just use $domNode->parentNode; to find the parent node.
In your example, the parent node of $importnode is null, because it has been imported into the document, and therefore does not have a parent yet. You need to attach it to another element before it has a parent.