PHP DOM: How to move element into default namespace?

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?

It is easier if you use a converter xml to array and backwards minimal reproducible example[1] [1]: stackoverflow.com/questions/1397036/… — AURIGADL
– AURIGADL, Commented Feb 22, 2013 at 17:21
I just realized that changing the namespace of a node (here: from a to default) is the same as renaming the node. So this question can be marked as a duplicate of the question "Rename an XML node using PHP", which already has a decent answer. — feklee
– feklee, Commented Feb 22, 2013 at 23:30
I now found a robust solution which may be worthy an answer, despite the fact that moving to default namespace is akin to renaming. — feklee
– feklee, Commented Feb 26, 2013 at 15:19
The aforementioned solution is simply to create a wrapper for the rename function from my answer to that other question: function moveToDefaultNamespace($element) { renameElement($element, $element->localName); } — feklee
– feklee, Commented Feb 26, 2013 at 16:18

feklee · Accepted Answer · 2013-02-22 18:52:32Z

3

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();

edited Feb 22, 2013 at 18:52

feklee

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answered Feb 22, 2013 at 17:17

hek2mgl

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14 Comments

feklee Over a year ago

Thanks! I edited your code a little bit, mainly fixed syntax, and added the cloneNode definition from the comment that you linked to. In the end this is actually what I proposed in my question (copy all children), but of course it's nice to have a ready-made function.

hek2mgl Over a year ago

Fine. I just didn't wanted to reproduce the code from the comment and also wanted to keep the code as short as possible

feklee Over a year ago

Had to tweak the function somewhat. I noticed, it doesn't remove the namespace prefix, i.e. in the original form it preserves <a:some>, while I want plain <some>.

hek2mgl Over a year ago

Please don't edit too much. My answer - as is - worked as you expected. I have tested it

feklee Over a year ago

I've tested it too: There were syntax errors. Please don't understand me wrong: Your answer is great! Still I will wait a little bit before marking it as accepted.

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