Hey,

So I am currently working on CMS that will automate the process of creating an XML file with data from form inputs. I know how to read and write XML using SimpleXML and the DOM.

My question is...how do you write children to a specified node in a document? For example I have this:

<?xml version="1.0"?>
<shell>
     <chapter id="01">
          <screen id="01">
               <background>...</background>
          </screen>
          <screen id="02" />
     </chapter>
</shell>

What I want to do is be able to append children to the screen node where the id="02". In addition, I will have to be able to append children to any number of screen nodes. There is not a set number of screen nodes per file. Any help would be awesome!

Use the xpath function to find matching elements and then adjust the element.

For example:

PHP Code:

<?php
$original_xml = '<'.'?xml version="1.0"?>
<shell>
     <chapter id="01">
          <screen id="01">
               <background>...</background>
          </screen>
          <screen id="02" />
     </chapter>
</shell>';

$xml_obj = new SimpleXMLElement($original_xml);

if (($screens = $xml_obj->xpath('/shell/chapter/screen[@id=02]')) !== false) {
  $screens[0]->addChild('background','***');
}


echo '<pre>', htmlspecialchars($xml_obj->asXML()), '</pre>';
?>

Ok, another question:

I have figured out how to add children to the node containing a specific attribute. However, how would I then add an attribute to a child within that node.

For example, I select a node with a specific attribute as such:

$snData = $xml->xpath('/shell/chapter/screen[@id=' . $snID . ']');
$snData[0]->addChild('background', $bground);

This works fine. However, I need to then add an attribute to a child within that. I thought I could used something like this:

$snData = $xml->xpath('/shell/chapter/screen[@id=' . $snID . ']/background');
$snData[0]->addAttribute('type', 'video');

But it does not work and I get error messages. Any suggestions?

Never mind, I figured it out. I just had to used double slashes instead of a single slash. The code now looks like this:

$snData = $xml->xpath('/shell/chapter/screen[@id=' . $snID . ']//background');
$snData[0]->addAttribute('type','video');

Thanks for posting your solution. I tried your error code, though, and did not get an error. What was the reported error and the XML you were working with?

Also, when you add a child, the addChild method returns a reference to the child node, so you could also add the attribute to the node w/o having to call a second xpath:

PHP Code:

<?php
$original_xml = '<'.'?xml version="1.0"?>
<shell>
     <chapter id="01">
          <screen id="01">
               <background>...</background>
          </screen>
          <screen id="02" />
     </chapter>
</shell>';

$xml_obj = new SimpleXMLElement($original_xml);

if (($screens = $xml_obj->xpath('/shell/chapter/screen[@id=02]')) !== false) {
  $child_node = $screens[0]->addChild('background','***');
  $child_node->addAttribute('type', 'video');
}

echo '<pre>', htmlspecialchars($xml_obj->asXML()), '</pre>';
?>