DOMDocument::registerNodeClass

(PHP 5 >= 5.2.0, PHP 7)

DOMDocument::registerNodeClass — Register extended class used to create base node type

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public DOMDocument::registerNodeClass ( string $baseclass , string $extendedclass ) : bool

This method allows you to register your own extended DOM class to be used afterward by the PHP DOM extension.

This method is not part of the DOM standard.

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baseclass

The DOM class that you want to extend. You can find a list of these classes in the chapter introduction.

extendedclass

Your extended class name. If NULL is provided, any previously registered class extending baseclass will be removed.

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5.2.2 Prior to 5.2.2, a previously registered extendedclass had to be unregistered before being able to register a new class extending the same baseclass.

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Example #1 Adding a new method to DOMElement to ease our code

<?php

class myElement extends DOMElement {
   function appendElement($name) { 
      return $this->appendChild(new myElement($name));
   }
}

class myDocument extends DOMDocument {
   function setRoot($name) { 
      return $this->appendChild(new myElement($name));
   }
}

$doc = new myDocument();
$doc->registerNodeClass('DOMElement', 'myElement');

// From now on, adding an element to another costs only one method call ! 
$root = $doc->setRoot('root');
$child = $root->appendElement('child');
$child->setAttribute('foo', 'bar');

echo $doc->saveXML();

?>

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<?xml version="1.0"?>
<root><child foo="bar"/></root>

Example #2 Retrieving elements as custom class

<?php
class myElement extends DOMElement {
    public function __toString() {
        return $this->nodeValue;
    }
}

$doc = new DOMDocument;
$doc->loadXML("<root><element><child>text in child</child></element></root>");
$doc->registerNodeClass("DOMElement", "myElement");

$element = $doc->getElementsByTagName("child")->item(0);
var_dump(get_class($element));

// And take advantage of the __toString method..
echo $element;
?>

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string(9) "myElement"
text in child

Example #3 Retrieving owner document

When instantiating a custom DOMDocument the ownerDocument property will refer to the instantiated class, meaning there is no need (and in fact not possible) to use DOMDocument::registerNodeClass() with DOMDocument

<?php
class myDOMDocument extends DOMDocument {
}

class myOtherDOMDocument extends DOMDocument {
}

// Create myDOMDocument with some XML
$doc = new myDOMDocument;
$doc->loadXML("<root><element><child>text in child</child></element></root>");

$child = $doc->getElementsByTagName("child")->item(0);

// The current owner of the node is myDOMDocument
var_dump(get_class($child->ownerDocument));

// Import a node from myDOMDocument
$newdoc = new myOtherDOMDocument;
$child = $newdoc->importNode($child);

// The new owner of the node has changed to myOtherDOMDocument
var_dump(get_class($child->ownerDocument));
?>

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string(13) "myDOMDocument"
string(18) "myOtherDOMDocument"