Generate a stylesheet into a Woocommerce plugin

[meowmix]

Hello!

 

I'm trying to tweak a woocommerce application that generate orders in an XML format. I've been trying to add a stylesheet declaration but I can't seem to figure out what I'm doing wrong (keep in mind that I'm self taught).

 

When exporting the XML file, I'd like this to be right under the XML version declaration : 

 

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

 

I have attached the PHP file that I'm trying to tweak.

 

So far I've tried to add :
 

$xslt = $xml->createProcessingInstruction('xml-stylesheet', 'type="text/xsl" href="base.xsl"');

 

but that didn't work. I've been searching for 2 days and I can't seem to solve this. Perhaps someone can point me in the right direction as to where I can find my answer or what I'd need to learn in order to fully understand how this works?

 

Thank you! 

class-wc-customer-order-xml-export-suite-writer.php

[meowmix]

No luck?