Question

The problem seems straightforward, but I’m having trouble getting access to the tag name of a SimpleXMLElement.

Let’s say I have the follow XML structure:

<xml>
     <oldName>Stuff</oldName>
</xml>

And I want it to look like this:

<xml>
     <newName>Stuff</newName>
</xml>

Is this possible to do without doing a copy of the entire object?

I’ve started to realize the errors of the ways I am approaching this problem. It seems that I need to convert my SimpleXMLElement into a DOM object. Upon doing so I find it very hard to manipulate the object in the way I want (apparently renaming tags in a DOM isn’t easy to do for a reason).

So… I am able to import my SimpleXMLElement into a DOM object with the import, but I am finding it difficult to do the clone.

Is the following the right thinking behind cloning a DOM object or am I still way off:

$old = $dom->getElementsByTagName('old')->item(0); // The tag is unique in my case
$new = $dom->createElement('new');

/* ... some recursive logic to copy attributes and children of the $old node ... */

$old->ownerDocument->appendChild($new);
$new->ownerDocument->removeChild($old);

Answer 1

Here’s what’s probably the simplest way to copy a node’s children and attributes without using XSLT:

function clonishNode(DOMNode $oldNode, $newName, $newNS = null)
{
    if (isset($newNS))
    {
        $newNode = $oldNode->ownerDocument->createElementNS($newNS, $newName);
    }
    else
    {
        $newNode = $oldNode->ownerDocument->createElement($newName);
    }

    foreach ($oldNode->attributes as $attr)
    {
        $newNode->appendChild($attr->cloneNode());
    }

    foreach ($oldNode->childNodes as $child)
    {
        $newNode->appendChild($child->cloneNode(true));
    }

    $oldNode->parentNode->replaceChild($newNode, $oldNode);
}

Which you can use this way:

$dom = new DOMDocument;
$dom->loadXML('<foo><bar x="1" y="2">x<baz/>y<quux/>z</bar></foo>');

$oldNode = $dom->getElementsByTagName('bar')->item(0);
clonishNode($oldNode, 'BXR');

// Same but with a new namespace
//clonishNode($oldNode, 'newns:BXR', 'http://newns');

die($dom->saveXML());

It will replace the old node with a clone with a new name.

Attention though, this is a copy of the original node’s content. If you had any variable pointing to the old nodes, they are now invalid.