Enumerate registered namespaces of a PHP DOMDocument object

Question

Hello world,

For one of my projects, I'm using the DOMDocument class to load and manipulate XML documents.

I'd need to retrieve every namespace used in the document; however, I can't find how I'd do that. The DOMDocument class has methods to get the namespace prefix of an URI or the URI of a namespace prefix, but I've seen nothing to actually enumerate registered namespaces.

The SimpleXML library has a getNamespaces() method for that. Is there an equivalent for DOMDocument?

Answer 1

I think you want getElementsByTagNameNS()

Answer 2

DOM does not have such a function afaik. I've looked briefly at the source code of SimpleXml and I think it iterates the loaded XML and collects the namespaces (my C is very bad). The easiest solution would be to fetch the namespaces by importing the DOM dom into SimpleXml for this purpose. Maybe like this:

class DomUtils
{
    public static function getNamespaces($dom)
    {
        $sxe = simplexml_import_dom($dom);
        return $sxe->getNamespaces(); 
    }

    public static function getDocNamespaces($dom)
    {
        $sxe = simplexml_import_dom($dom);
        return $sxe->getDocNamespaces();
    }
}

You could also try to get all namespaces with XPath. See the following question and answers:

• How to retrieve namespaces in XML files using Xpath