How to replace XML node with SimpleXMLElement PHP

Question

I have the following XML (string1):

<?xml version="1.0"?>
<root>
   <map>
      <operationallayers>
         <layer label="Security" type="feature" visible="false" useproxy="true" usePopUp="all" url="http://stackoverflow.com"/>
      </operationallayers>
   </map>
</root>

And I have this piece of XML (string2):

<operationallayers>
    <layer label="Teste1" type="feature" visible="false" useproxy="true" usePopUp="all" url="http://stackoverflow.com"/>
    <layer label="Teste2" type="dynamic" visible="false" useproxy="true" usePopUp="all" url="http://google.com"/>
</operationallayers>

I used the funcion simplexml_load_string to import both to the respectives var:

$xml1 = simplexml_load_string($string1);
$xml2 = simplexml_load_string($string2);

Now, I want to replace the node 'operationallayers' of the string1 for the node 'operationallayers' of the string2, but how?

The class SimpleXMLElement does not have a method 'replaceChild' like the DOM has.

Answer 1

Similar to what has been outlined in SimpleXML: append one tree to another you can import those nodes into DOMDocument because as you write:

"The class SimpleXMLElement dont have a method 'replaceChild' like the DOM."

So when you import into DOM you can use those:

$xml1 = simplexml_load_string($string1);
$xml2 = simplexml_load_string($string2);

$domToChange = dom_import_simplexml($xml1->map->operationallayers);
$domReplace  = dom_import_simplexml($xml2);
$nodeImport  = $domToChange->ownerDocument->importNode($domReplace, TRUE);
$domToChange->parentNode->replaceChild($nodeImport, $domToChange);

echo $xml1->asXML();

Which gives you the following output (non-beautified):

<?xml version="1.0"?>
<root>
   <map>
      <operationallayers>
    <layer label="Teste1" type="feature" visible="false" useproxy="true" usePopUp="all" url="http://stackoverflow.com"/>
    <layer label="Teste2" type="dynamic" visible="false" useproxy="true" usePopUp="all" url="http://google.com"/>
</operationallayers>
   </map>
</root>

Additionally you can then take this and add the operation to your SimpleXMLElement so that it's easily wrapped. This works by extending from SimpleXMLElement:

/**
 * Class MySimpleXMLElement
 */
class MySimpleXMLElement extends SimpleXMLElement
{
    /**
     * @param SimpleXMLElement $element
     */
    public function replace(SimpleXMLElement $element) {
        $dom     = dom_import_simplexml($this);
        $import  = $dom->ownerDocument->importNode(
            dom_import_simplexml($element),
            TRUE
        );
        $dom->parentNode->replaceChild($import, $dom);
    }
}

Usage Example:

$xml1 = simplexml_load_string($string1, 'MySimpleXMLElement');
$xml2 = simplexml_load_string($string2);

$xml1->map->operationallayers->replace($xml2);

Related: In SimpleXML, how can I add an existing SimpleXMLElement as a child element?.

Last time I extended SimpleXMLElement on Stackoverflow was in an answer to the "Read and take value of XML attributes" question.