使用PHP识别XML元素并将父节点复制到外部XML文件

Question

I am parsing an XML file (source.xml) in PHP and need to identify instances where the <property> node contains the <rent> element.

Once identified the entire <property> parent node for that entry should be copied to a separate XML file (destination.xml).

On completion of the copy that <property> node should be removed from the source.xml file.

Here is an example of the source.xml file:

<?xml version="1.0" encoding="utf-8"?>
<root>
    <property>
        ...
        <rent>
            <term>long</term>
            <freq>month</freq>
            <price_peak>1234</price_peak>
            <price_high>1234</price_high>
            <price_medium>1234</price_medium>
            <price_low>1234</price_low>
        </rent>
        ...
    </property>
</root>

I've tried using DOM with the below code however I'm not getting any results at all despite their being hundreds of nodes that match the above requisites. Here is what I have so far:

$destination = new DOMDocument;
$destination->preserveWhiteSpace = true;
$destination->load('destination.xml');

$source = new DOMDocument;
$source->load('source.xml');

$xp = new DOMXPath($source);

foreach ($xp->query('/root/property/rent[term/freq/price_peak/price_high/price_medium/price_low]') as $item) {

    $newItem = $destination->documentElement->appendChild(

        $destination->createElement('property')

    );

    foreach (array('term', 'freq', 'price_peak', 'price_high', 'price_medium', 'price_low') as $elementName) {

        $newItem->appendChild(
            $destination->importNode(
                $item->getElementsByTagName($elementName)->property(0),
                true
            )
        );
    }
}

$destination->formatOutput = true;
echo $destination->saveXml();

I've only started learning about DOMDocument and it's uses so I'm obviously messing up somewhere so any help is appreciated. Many thanks.

Answer 1

The difficulty is when your trying to copy a node from one document to another. You can try and re-create the node, copying all of the components across, but this is hard work (and prone to errors). Instead you can import the node from one document to another using importNode. The second parameter says copy all child elements as well.

Then deleting the element from the original document is a case of getting the item to 'delete itself from it's parent' which sounds odd, but thats how this code works.

<?php
error_reporting ( E_ALL );
ini_set ( 'display_errors', 1 );

$destination = new DOMDocument;
$destination->preserveWhiteSpace = true;
$destination->loadXML('<?xml version="1.0" encoding="utf-8"?><root></root>');

$source = new DOMDocument;
$source->load('NewFile.xml');

$xp = new DOMXPath($source);
$destRoot = $destination->getElementsByTagName("root")->item(0);
foreach ($xp->query('/root/property[rent]') as $item) {
    $newItem = $destination->importNode($item, true);
    $destRoot->appendChild($newItem);
    $item->parentNode->removeChild($item);
}

echo "Source:".$source->saveXML();
$destination->formatOutput = true;
echo "destination:".$destination->saveXml();

With the destination, I prime it with the basic <root> element and then add in the contents from there.