Using PHP to include a colon within a XML child elements name

Question

I'm trying to have my sitemap update automatically as pages are added. I'm defining var containing the child name I need, which is including a colon character. PHP or XML is removing the colon and word to the right or left of it. How can I keep that colon in the child elements name?

I'm using this:

<?php
$imagechild = 'image:image';
$imageloc = 'image:loc';

 $xml=simplexml_load_file("sitemap.xml");

 $map = $xml->addChild('url');
   $map->addChild('loc', "http:/some website".$page_path);

 $img = $map->addChild($imagechild);
   $img->addChild($imageloc, $img_link);

     $xml->saveXML('sitemap.xml');
?>

I'm getting this:

      <url>
        <loc>web url</loc>
        <image>
          <loc>image url</loc>
        </image>
      </url>

I need this

      <url>
        <loc>web url</loc>
        <image:image>
          <loc>image url</loc>
        </image:image>
      </url>

Thank you in advance!

Answer 1

If an element name contains a : then the part before the : is the namespace prefix. If you are using namespace prefixes then you need to define the namespace somewhere in the document.

Check the manual of SimpleXmlElement::addChild(). You need to pass the namespace uri as the third element in order to make it work:

$img = $map->addChild($imagechild, '',  'http://your.namspace.uri/path');

---

I would encourage you to use the DOMDocument class in favour of the simple_xml extension. It can handle namespaces much more properly. Check this example:

Assuming you have this xml:

<?xml version="1.0"?>
<map>
</map>

And this PHP code:

$doc = new DOMDocument();
$doc->load("sitemap.xml");

$map = $doc->documentElement;

// Define the xmlns "image" in the root element
$attr = $doc->createAttribute('xmlns:image');
$attr->nodeValue = 'http://your.namespace.uri/path';
$map->setAttributeNode($attr);

// Create new elements
$loc = $doc->createElement('loc', 'your location comes here');
$image = $doc->createElement('image:image');
$imageloc = $doc->createElement('loc', 'your image location comes here');

// Add them to the tree
$map->appendChild($loc);
$image->appendChild($imageloc);
$map->appendChild($image);

// Save to file
file_put_contents('sitemap.xml', $doc->saveXML());

You'll get this output:

<?xml version="1.0"?>
<map xmlns:image="http://your.namespace.uri/path">
  <loc>your location comes here</loc>
  <image:image>
    <loc>your image location comes here</loc>
  </image:image>
</map>