How to add nodes to a multi-level XML from an array? - php

Question

I have an array $arr=array("A-B-C-D","A-B-E","A-B-C-F") and my expected output of the XML should be
<root>
<A>
<B>
<C>
<D></D>
<F></F>
</C>
<E></E>
</B>
</A>
</root>
I have already done the code that creates a new node of the XML for the first array element i.e. A-B-C-D. But when I move to the second element I need to check how many nodes are already created (A-B) and then add the new node based on that in the proper position.
So how do I traverse the XML and find the exact position where the new node should be attached?
my current code looks like this
$arr=explode("-",$input);
$doc = new DomDocument();
$doc->formatOutput=true;
$doc->LoadXML('<root/>');
$root = $doc->documentElement;
$comm = $doc->createElement('comm');
$root->appendChild($comm);
foreach($arr as $a2) {
$newcomm = $doc->createElement($a2);
$community->appendChild($newcomm);
$community=$newcomm;
}
Should I use xpath or some other method will be easier?

Answer 1

To stick with using DOMDocument, I've added an extra loop to allow you to add all of the original array items in. The main thing is before adding a new item in, check if it's already there...
<?php
error_reporting(E_ALL);
ini_set('display_errors', 1);
$set=array("A-B-C-D","A-B-E","A-B-C-F-G", "A-B-G-Q");
$doc = new DomDocument();
$doc->formatOutput=true;
$doc->LoadXML('<root/>');
foreach ( $set as $input ) {
$arr=explode("-",$input);
$base = $doc->documentElement;
foreach($arr as $a2) {
$newcomm = null;
// Decide if the element already exists.
foreach ( $base->childNodes as $nextElement ) {
if ( $nextElement instanceof DOMElement
&& $nextElement->tagName == $a2 ) {
$newcomm = $nextElement;
}
}
if ( $newcomm == null ) {
$newcomm = $doc->createElement($a2);
$base->appendChild($newcomm);
}
$base=$newcomm;
}
}
echo $doc->saveXML();
As there is no quick way ( as far as I know) to check for a child with a specific tag name, it just looks through all of the child elements for a DOMElement with the same name.
I started using getElementByTagName, but this finds any child node with the name and not just at the current level.
The output from above is...
<?xml version="1.0"?>
<root>
<A>
<B>
<C>
<D/>
<F>
<G/>
</F>
</C>
<E/>
<G>
<Q/>
</G>
</B>
</A>
</root>
I added a few other items in to show that it adds things in at the right place.