如何使用命名空间获取属性的值

I'd like to get the content of the attribute xsi:schemaLocation. It's works perfectly with getElementsByTagName in php (and foreach after) but it's ugly, right ?

How to get the same content with a simple Xpath query ?

Here a short example of the xml content :

<?xml version="1.0" encoding="utf-8"?>
<gpx xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" version="1.0" creator="blabla" xsi:schemaLocation="http://www.topografix.com/GPX/1/0 http://www.topografix.com/GPX/1/0/gpx.xsd http://www.groundspeak.com/cache/1/0/1 http://www.groundspeak.com/cache/1/0/1/cache.xsd" xmlns="http://www.topografix.com/GPX/1/0">
...
</gpx>

Thanks!

Using the SimpleXMLElement class you can easily get the attribute xsi:schemaLocation's value:

<?php
$xml = <<<XML
<?xml version="1.0" encoding="utf-8"?>
<gpx xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" version="1.0" creator="blabla" xsi:schemaLocation="http://www.topografix.com/GPX/1/0 http://www.topografix.com/GPX/1/0/gpx.xsd http://www.groundspeak.com/cache/1/0/1 http://www.groundspeak.com/cache/1/0/1/cache.xsd" xmlns="http://www.topografix.com/GPX/1/0">
</gpx>
XML;

$sxe = new SimpleXMLElement($xml);
$schemaLocation = $sxe->attributes('xsi', true)->schemaLocation;

echo (string) $schemaLocation;

Typically you need to register the namespaces you want to use with the XPath library first. Then you can query the attribute by including namespace prefix along with the name.

So let's assume you're using DOMXPath, you might register the following namespaces:

$xpath = new DOMXPath($doc);
$xpath->registerNamespace("xsi","http://www.w3.org/2001/XMLSchema-instance");
$xpath->registerNamespace("gpx", "http://www.topografix.com/GPX/1/0");

And then you can query the schemaLocation attribute with something like this:

$xpath->query("/gpx:gpx/@xsi:schemaLocation",$doc);