php only appending 3 out of 5 child nodes - php

Question

This code is only appending 3 of the 5 name nodes. Why is that?
Here is the original XML:
It has 5 name nodes.
<?xml version='1.0'?>
<products>
<product>
<itemId>531670</itemId>
<modelNumber>METRA ELECTRONICS/MOBILE AUDIO</modelNumber>
<categoryPath>
<category><name>Buy</name></category>
<category><name>Car, Marine & GPS</name></category>
<category><name>Car Installation Parts</name></category>
<category><name>Deck Installation Parts</name></category>
<category><name>Antennas & Adapters</name></category>
</categoryPath>
</product>
</products>
Then is run this PHP code. which is suppossed to appened ALL name nodes into the product node.
<?php
// load up your XML
$xml = new DOMDocument;
$xml->load('book.xml');
// Find all elements you want to replace. Since your data is really simple,
// you can do this without much ado. Otherwise you could read up on XPath.
// See http://www.php.net/manual/en/class.domxpath.php
//$elements = $xml->getElementsByTagName('category');
// WARNING: $elements is a "live" list -- it's going to reflect the structure
// of the document even as we are modifying it! For this reason, it's
// important to write the loop in a way that makes it work correctly in the
// presence of such "live updates".
foreach ($xml->getElementsByTagName('product') as $product ) {
foreach($product->getElementsByTagName('name') as $name ) {
$product->appendChild($name );
}
$product->removeChild($xml->getElementsByTagName('categoryPath')->item(0));
}
// final result:
$result = $xml->saveXML();
echo $result;
?>
The end result is this and it only appends 3 of the name nodes:
<?xml version="1.0"?>
<products>
<product>
<itemId>531670</itemId>
<modelNumber>METRA ELECTRONICS/MOBILE AUDIO</modelNumber>
<name>Buy</name>
<name>Antennas & Adapters</name>
<name>Car Installation Parts</name>
</product>
</products>
Why is it only appending 3 of the name nodes?

Answer 1

You can temporarily add the name elements to an array before appending them, owing to the fact that you're modifying the DOM in real time. The node list generated by getElementsByTagName() may change as you are moving nodes around (and indeed that appears to be what's happening).
<?php
// load up your XML
$xml = new DOMDocument;
$xml->load('book.xml');
// Array to store them
$append = array();
foreach ($xml->getElementsByTagName('product') as $product ) {
foreach($product->getElementsByTagName('name') as $name ) {
// Stick $name onto the array
$append[] = $name;
}
// Now append all of them to product
foreach ($append as $a) {
$product->appendChild($a);
}
$product->removeChild($xml->getElementsByTagName('categoryPath')->item(0));
}
// final result:
$result = $xml->saveXML();
echo $result;
?>
Output, with all values appended:
<?xml version="1.0"?>
<products>
<product>
<ItemId>531670</ItemId>
<modelNumber>METRA ELECTRONICS/MOBILE AUDIO</modelNumber>
<name>Buy</name><name>Car, Marine & GPS</name><name>Car Installation Parts</name><name>Deck Installation Parts</name><name>Antennas & Adapters</name></product>
</products>

Answer 2

You're modifying the DOM tree as you're pulling results from it. Any modifications to the tree that cover the results of a previous query operation (your getElementsByTagName) invalidate those results, so you're getting undefined results. This is especially true of operations that add/remove nodes.

Answer 3

You're moving nodes as you're iterating through them so 2 are being skipped. I'm not a php guy so I can't give you the code to do this, but what you need to do is build a collection of the name nodes and iterate through that collection in reverse.

Answer 4

A less complicated way to do it is to manipulate the nodes with insertBefore
foreach($xml->getElementsByTagName('name') as $node){
$gp = $node->parentNode->parentNode;
$ggp = $gp->parentNode;
// move the node above gp without removing gp or parent
$ggp->insertBefore($node,$gp);
}
// remove the empty categoryPath node
$ggp->removeChild($gp);