PHP - Duplicate XML node using Simple XML

问题:

I need to load an XML source using Simple XML, duplicate an existing node with all his children, then customize an attribute of this new node before rendering XML. Any suggestion?

回答1:

SimpleXML can't do this, so you'll have to use DOM. The good news is that DOM and SimpleXML are two sides of the same coin, libxml. So no matter whether you're using SimpleXML or DOM, you're working on the same tree. Here's an example:

$thing = simplexml_load_string(
    '<thing>
        <node n="1"><child/></node>
    </thing>'
);

$dom_thing = dom_import_simplexml($thing);
$dom_node  = dom_import_simplexml($thing->node);
$dom_new   = $dom_thing->appendChild($dom_node->cloneNode(true));

$new_node  = simplexml_import_dom($dom_new);
$new_node['n'] = 2;

echo $thing->asXML();

---

If you're doing that kind of thing a lot, you can try SimpleDOM, which is an extension to SimpleXML that lets you use DOM's methods directly, without converting from and to DOM objects.

include 'SimpleDOM.php';
$thing = simpledom_load_string(
    '<thing>
        <node n="1"><child/></node>
    </thing>'
);

$new = $thing->appendChild($thing->node->cloneNode(true));
$new['n'] = 2;

echo $thing->asXML();

回答2:

With SimpleXML, the best way I've found is a workaround. It's pretty bobo, but it works:

// Strip it out so it's not passed by reference
$newNode = new SimpleXMLElement($xml->someNode->asXML());

// Modify your value
$newnode['attribute'] = $attValue;

// Create a dummy placeholder for it wherever you need it
$xml->addChild('replaceMe');

// Do a string replace on the empty fake node
$xml = str_replace('<replaceMe/>',$newNode->asXML(),$xml->asXML());

// Convert back to the object
$xml = new SimpleXMLElement($xml); # leave this out if you want the xml

Since it's a workaround for a feature that doesn't seem to be there in SimpleXML, you'll need to be aware that I expect this would break any object references you've defined up to this point, if any.