Using insertBefore method in php - php

Question

I have actually asked this before, but alas the PC got nicked that I had the solution on, and I no longer can get the previous solution to work.
I'm trying to add a new element to the XML below:
<?xml version="1.0" encoding="ISO-8859-1"?>
<data>
<comments>
<comment>
<date>20120509</date>
<time>10:21:05</time>
<name>Lucy</name>
<text>Hello etc</text>
</comment>
<comment> ...etc
The PHP code I'm using is:
$xml = new DOMDocument('1.0', 'utf-8');
$xml->load(filename.xml);
$parent = $xml->firstChild;
$refnode = $parent->firstChild;
$new = $parent->insertBefore($xml->createElement('comment'), $refnode);
However, this adds a new "comment" immediately after the "data" tag, and if I try to add children (such as "date", "time" etc...) with $new->addChild(tag, value), I get an "undefined method" error. I've tried all manner of permutations, but nothing works.
desired result would be:
<?xml version="1.0" encoding="ISO-8859-1"?>
<data>
<comments>
*<comment>
<date>20140225</date>
<time>17:39:05</time>
<name>Derek</name>
<text>New comment text</text>
</comment>*
<comment>
<date>20120509</date>
<time>10:21:05</time>
<name>Lucy</name>
<text>Hello etc</text>
</comment>
<comment> ...etc

Answer 1

Your XML file most likely contained the whitespace characters like in your example. These are interpreted as text nodes, which renders firstChild useless to obtain one of those elements you want.
You have to iterate over the children instead and get the first one, which is actually a DOMElement. Also you had to go one level deeper than you did. See appended sourcecode which outputs the result you want.
<?php
$xml = new DOMDocument();
$xml->loadXML('<?xml version="1.0" encoding="UTF-8"?>
<data>
<comments>
<comment>
<date>20120509</date>
<time>10:21:05</time>
<name>Lucy</name>
<text>Hello etc</text>
</comment>
</comments>
</data>');
$parent = $xml->firstChild;
foreach ($parent->childNodes as $c) {
if ($c instanceof DOMElement) {
$refnode = $c;
break;
}
}
foreach ($refnode->childNodes as $c) {
if ($c instanceof DOMElement) {
$refnode2 = $c;
break;
}
}
$insert = $xml->createElement('comment', 'test');
$refnode->insertBefore($insert, $refnode2);
echo $xml->saveHTML();