简单的xpath查询，但没有结果

Question

Trying to get all URLs values from xml.

I have hundreds of entry exactly in the form like e.g. this entry 16:

<?xml version="1.0" encoding="utf-8" ?>
<root xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
   <entries>
   <entry id="16">
      <revision number="1" status="accepted" wordclass="v" nounclasses="" unverified="false"></revision>
      <media type="audio" url="http://website.com/file/65.mp3" />
      </entry>
   <entry id="17">
      ....
   </entry>
</entries>
</root>

I am using this code but cannot get it to work. Why?

$doc = new DOMDocument;

$doc->Load('data.xml');

$xpath = new DOMXPath($doc);

$query = '//root/entries/entry/media';

$entries = $xpath->query($query);

What is the correc query for that? Best would be to only get the url value.

Answer 1

Your query probably returns the proper elements, but by default gives you the content of the media tag ( which in your case are empty, since the tag is self-closing ).

To get the url attribute of the tag you should use getAttribute(), example :

$entries = $xpath->query('//root/entries/entry/media');
foreach($entries as $entry) { 
  print $entry->getAttribute("url")."<br/>";
}

Or you should just xpath-query the attribute instead and read out it's value:

$urlAttributes = $xpath->query('//root/entries/entry/media/@url');
                                                          #####
foreach ($urlAttributes as $urlAttribute)
{ 
    echo $urlAttribute->value, "<br/>
";
                        #####
}

See DOMAttr::$value^Docs:

value

---

The value of the attribute