Question

<node1>
    <node2>
         <node3>
         </node3>
         <node3>
         </node3>
         <node3>
         </node3>
    </node2>

    <node2>
         <node3>
         </node3>
         <node3>
         </node3>
         <node3>
         </node3>
    </node2>

    ...
 </node1>

Let’s say I have this structure in an XML document. I would like to be able to comment a node and all its content and to uncomment it if necessary, using PHP. I tried to find a way looking at DOMDocument’s documentation and SimpleXML’s documentation without success.

Edit: Just to clarify: I found how to comment a node, but not how to uncomment it.

Answer 1

Comments can be created using DOMDocument::createComment(). Replacing comments with actual nodes is just like replacing any other node type, use DOMElement::replaceChild().

$doc = new DOMDocument;
$doc->loadXML('<?xml version="1.0"?>
<example>
    <a>
        <aardvark/>
        <adder/>
        <alligator/>
    </a>
</example>
');

$node = $doc->getElementsByTagName('a')->item(0);

// Comment by making a comment node from target node's outer XML
$comment = $doc->createComment($doc->saveXML($node));
$node->parentNode->replaceChild($comment, $node);
echo $doc->saveXML();

// Uncomment by replacing the comment with a document fragment
$fragment = $doc->createDocumentFragment();
$fragment->appendXML($comment->textContent);
$comment->parentNode->replaceChild($fragment, $comment);
echo $doc->saveXML();

The (super-simplified) examples above should output something like:

<?xml version="1.0"?>
<example>
    <!--<a>
        <aardvark/>
        <adder/>
        <alligator/>
    </a>-->
</example>
<?xml version="1.0"?>
<example>
    <a>
        <aardvark/>
        <adder/>
        <alligator/>
    </a>
</example>

Reference

• DOMDocument::createComment() to create <-- comments -->
• DOMElement::replaceChild() to swap nodes around
• DOMDocument::createDocumentFragment() to create a document fragment
• DOMDocumentFragment::appendXML() to append a string of xml to a fragment
• DOMDocument::saveXML() to get the XML for an element
• DOMCharacterData->data to get the content of a comment