PHP DOM: How to move element into default namespace? - php

Question

What I tried and what doesn't work:
Input:
$d = new DOMDocument();
$d->formatOutput = true;
// Out of my control:
$someEl = $d->createElementNS('http://example.com/a', 'a:some');
// Under my control:
$envelopeEl = $d->createElementNS('http://example.com/default',
'envelope');
$d->appendChild($envelopeEl);
$envelopeEl->appendChild($someEl);
echo $d->saveXML();
$someEl->prefix = null;
echo $d->saveXML();
Output is invalid XML after substitution:
<?xml version="1.0"?>
<envelope xmlns="http://example.com/default">
<a:some xmlns:a="http://example.com/a"/>
</envelope>
<?xml version="1.0"?>
<envelope xmlns="http://example.com/default">
<:some xmlns:a="http://example.com/a" xmlns:="http://example.com/a"/>
</envelope>
Note that <a:some> may have children. One solution would be
to create a new <some>, and copy all children from <a:some> to <some>. Is
that the way to go?

Answer 1

This is really an interesting question. My first intention was to clone the <a:some> node, remove the xmlns:a attribute, remove the <a:some> and insert the clone - <a>. But this will not work, as PHP does not allow to remove the xmlns:a attribute like any regular attribute.
After some struggling with DOM methods of PHP I started to google the problem. I found this comment in the PHP documentation on this. The user suggest to write a function that clones the node manually without it's namespace:
<?php
/**
* This function is based on a comment to the PHP documentation.
* See: http://www.php.net/manual/de/domnode.clonenode.php#90559
*/
function cloneNode($node, $doc){
$unprefixedName = preg_replace('/.*:/', '', $node->nodeName);
$nd = $doc->createElement($unprefixedName);
foreach ($node->attributes as $value)
$nd->setAttribute($value->nodeName, $value->value);
if (!$node->childNodes)
return $nd;
foreach($node->childNodes as $child) {
if($child->nodeName == "#text")
$nd->appendChild($doc->createTextNode($child->nodeValue));
else
$nd->appendChild(cloneNode($child, $doc));
}
return $nd;
}
Using it would lead to a code like this:
$xml = '<?xml version="1.0"?>
<envelope xmlns="http://example.com/default">
<a:some xmlns:a="http://example.com/a"/>
</envelope>';
$doc = new DOMDocument();
$doc->loadXML($xml);
$elements = $doc->getElementsByTagNameNS('http://example.com/a', 'some');
$original = $elements->item(0);
$clone = cloneNode($original, $doc);
$doc->documentElement->replaceChild($clone, $original);
$doc->formatOutput = TRUE;
echo $doc->saveXML();