只在PHP DOM中选择没有名称空间/前缀的节点？

Question

I'm trying to read some RSS feeds with DOM in PHP like this one:

    <channel>
        <atom:link href='' rel='self' type='application/rss+xml' />
        <title>TechStuff</title>
        <link>http://www.howstuffworks.com</link>

To grab the link (<link></link>) I use this piece of code:

    $doc->getElementsByTagName('link')->item(0);

It works in all other RSS feeds that I have tried. But this one has placed <atom:link> before <link>, which means that it grabs <atom:link> instead.

So how do I do to only select nodes without a namespace?

Answer 1

You can tell whether a node has a namespace by checking ->prefix or ->namespaceURI:

foreach ($doc->getElementsByTagName('link') as $link) {
    if (strlen($link->prefix)) {
        continue;
    }
    // $link does not have prefix
}