Add xml-stylesheet tag simpleXML php

Hy guys this is my simple code:

$xml = new SimpleXMLElement('<p:FatturazioneElettronica xmlns:p="http://microsoft.com/wsdl/types/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://dummy.com"/>');

$xml->addAttribute("versione","FPR12");

$FatturaElettronicaHeader = $xml->addChild('FatturaElettronicaHeader',null,'http://dummy.com');

the xml results is:

<p:FatturazioneElettronica xmlns:p="http://microsoft.com/wsdl/types/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://dummy.com" versione="FPR12">

 <FatturaElettronicaHeader>
  <DatiTrasmissione>
   ....

How can add at the top of my xml "xml-stylesheet"?

<?xml-stylesheet type="text/xsl" href="fatturapa_v1.2.xsl" ?>

Solution

SimpleXML isn't very good at doing anything other than simple things (think that's were the name is very apt). The only way I can think of doing it is to use DOMDocument, which provides a richer API and you should be able to do it as follows...

$xmlD = new DOMDocument( "1.0", "ISO-8859-15" );
$xmlD->appendChild($xmlD->createProcessingInstruction('xml-stylesheet', 'type="text/xsl" href="fatturapa_v1.2.xsl"'));
$xmlD->appendChild($xmlD->importNode(dom_import_simplexml($xml)));

echo $xmlD->saveXML();

This creates a new DOMDocument instance and then adds a few things. First it uses createProcessingInstruction() to add the processing instruction for the style sheet. Then it imports the existing contents of your SimpleXML document (in $xml) and appends this to the end. The echo should give you a document something like...

<?xml version="1.0" encoding="ISO-8859-15"?>
<?xml-stylesheet type="text/xsl" href="fatturapa_v1.2.xsl"?>
<p:FatturazioneElettronica xmlns:p="http://microsoft.com/wsdl/types/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://dummy.com" versione="FPR12"/>