Using UBL/Oasis urn type namespaces fatal error

[coenjacobs]

Doing this:

$xml = new FluidXml('Invoice');
$xml->namespace('xmlns:cac', 'urn:oasis:names:specification:ubl:schema:xsd:CommonAggregateComponents-2');
$xml->namespace('xmlns:cbc', 'urn:oasis:names:specification:ubl:schema:xsd:CommonBasicComponents-2');
$xml->namespace('xmlns', 'urn:oasis:names:specification:ubl:schema:xsd:Invoice-2');
$xml->addChild('cbc:UBLVersionID', '2.0');

Results in this (paths stripped):

Fatal error: Uncaught Error: Call to a member function uri() on null in .../vendor/servo/fluidxml/source/FluidXml/FluidInsertionHandler.php:194 Stack trace: #0 .../vendor/servo/fluidxml/source/FluidXml/FluidInsertionHandler.php(259): FluidXml\FluidInsertionHandler->createElement('UBLVersionID', '2.0') #1 .../vendor/servo/fluidxml/source/FluidXml/FluidInsertionHandler.php(92): FluidXml\FluidInsertionHandler->insertStringSimple(Object(DOMElement), 'cbc:UBLVersionI...', '2.0', Object(Closure), Array) #2 .../vendor/servo/fluidxml/source/FluidXml/FluidInsertionHandler.php(26): FluidXml\FluidInsertionHandler->handleInsertion(Object(DOMElement), 'cbc:UBLVersionI...', '2.0', Object(Closure), Array) #3 /Users in .../vendor/servo/fluidxml/source/FluidXml/FluidInsertionHandler.php on line 194

As you can see in the error, the child I'm trying to add is throwing the error. This only happens when the namespace is used in the element name of the child. Am I adding the namespace wrong to the child element name? I've followed the Getting started guide on namespaces and there it appears to be used in the same way as I have shown above.

It also doesn't matter if I add the namespaces to the root element as attributes or not. Is this because the UBL/Oasis namespaces use the urn type notation of the namespaces perhaps?

[daniele-orlando]

Namespace identifiers must be declared without the xmlns: part, as illustrated in the Wiki.
Getting-Started: 8. Namespaces

Rewriting your code,

$xml = new FluidXml('Invoice');
$xml->namespace('cac', 'urn:oasis:names:specification:ubl:schema:xsd:CommonAggregateComponents-2');
$xml->namespace('cbc', 'urn:oasis:names:specification:ubl:schema:xsd:CommonBasicComponents-2');
$xml->namespace('inv', 'urn:oasis:names:specification:ubl:schema:xsd:Invoice-2');
$xml->addChild('cbc:UBLVersionID', '2.0');