Extra data in simplexml using namespaces

Question

I am trying to learn XML in php but there is something I dont understand when using namespaces.

This is my code

$xml_data = new SimpleXMLElement("<rss xmlns:g=\"http://base.google.com/ns/1.0\" version=\"2.0\"></rss>");

$make = $xml_data->addChild('channel');

$make->addChild('g:model', 'foo', 'g');
$make->addChild('g:model', 'bar', 'g');
header ("Content-Type:text/xml");
print_r($xml_data->asXML());

When looking at guides on the internet I expect to get this.

<rss xmlns:g="http://base.google.com/ns/1.0" version="2.0">
<channel>
<g:model>foo</model>
<g:model>bar</g:model>
</channel>
</rss>

But I get this

<rss xmlns:g="http://base.google.com/ns/1.0" version="2.0">
<channel>
<g:model xmlns:g="g">foo</model>
<g:model xmlns:g="g">bar</g:model>
</channel>
</rss>

Why do I get this extra xmlnsg:="g" and what does it do? Looking at other feeds, they dont seem to get this?

Thanks in advance!

Answer 1

You must omit the xmlns alias when adding the child, and provide the full xmlns in the 3rd parameter (not the alias):

$make->addChild('model', 'foo', 'http://base.google.com/ns/1.0');

You can use a technique like this to simplify / DRY up management of the namespaces

Re: What does <g:model xmlns:g="g">foo</model> do?
This overrides the previous definition of the g alias (and corrupts it in your case to g)