Get XML namespace of root node - php

Question

I receive xml like:
<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type="text/xsl" href="http://adress.pl/FeResourceServlet/localTemplate/template1/styl.xsl"?>
<wnio:Dokument
xmlns:adr="http://adress.pl/xml/schema/adress/2009/11/09/"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xmlns:ev="http://www.w3.org/2001/xml-events"
xmlns:inst="http://adress.pl/xml/schematy/instytucja/2009/11/16/"
xmlns:meta="http://adress.pl/xml/schematy/meta/2009/11/16/"
xmlns:oso="http://adress.pl/xml/schematy/osoba/2009/11/16/"
xmlns:str="http://adress.pl/xml/schematy/struktura/2009/11/16/" xmlns:wnio="http://epuap.gov.pl/FeResourceServlet/localTemplate/ZgloszenieBudowy/"
xmlns:xf="http://www.w3.org/2002/xforms"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xxforms="http://orbeon.org/oxf/xml/xforms"
xsi:schemaLocation="http://adress.pl/FeResourceServlet/localTemplate/template1/ http://epuap.gov.pl/FeResourceServlet/localTemplate/template1/schema.xsd">
...
My question is - How can I get a namespace of root?
Above my root node is wnio:Dokument and I know that wnio is "namespace of root" and name of root is Dokument.
But name and namespace can be changed. Then I will have root node but I wouldn't know namespace and name of root.
I used so far: SimpleXMLElement::getNamespaces and SimpleXMLElement::getDocNamespaces. But I received every namespace but I don't know which is root.
It's possible in PHP to get these information?

Answer 1

DOM nodes have a property $namespaceURI that returns the namespace of the node:
$document = new DOMDocument();
$document->loadXml(
'<wnio:Dokument xmlns:wnio="http://epuap.gov.pl/FeResourceServlet/localTemplate/ZgloszenieBudowy/"/>'
);
var_dump($document->documentElement->namespaceURI);
But namespaces are the most stable part of an XML document. A namespace specifies the format of the information. If the namespace changes the format changes and you will have to change the logic of your application.
You application need to know the format it reads and expect to get it. That is the namespace.
The namespace prefix on the other hand can change on any element node. You should expect a specific prefix, but you can and have to expect a specific namespace.
Here is an example:
$document = new DOMDocument();
$document->loadXml(
'<wnio:Dokument xmlns:wnio="http://epuap.gov.pl/FeResourceServlet/localTemplate/ZgloszenieBudowy/"/>'
);
$xpath = new DOMXpath($document);
$xpath->registerNamespace('w', 'http://epuap.gov.pl/FeResourceServlet/localTemplate/ZgloszenieBudowy/');
foreach ($xpath->evaluate('/w:Dokument') as $node) {
var_dump($node->nodeName);
}
Output:
string(13) "wnio:Dokument"

Answer 2

You can use DomDocument
$dom = new DOMDocument();
$response = $dom->loadXML($xml);//$xml is your xml string or file
$root = $dom->documentElement;//will return the document root element
$rootPrefix = $root->prefix;//getting the prefix of your element
$namespace = $root->lookupNamespaceURI($rootPrefix);//getting the namespace of the root element
The [documentElement][2] attribute it's a simple way to get the root element as a DOMElement.