php xml generation with xpath - php

Question

I wrote a small helper function to do basic search replace using xpath, because I found it easy to write manipulations very short and at the same time easy to read and understand.
Code:
<?php
function xml_search_replace($dom, $search_replace_rules) {
if (!is_array($search_replace_rules)) {
return;
}
$xp = new DOMXPath($dom);
foreach ($search_replace_rules as $search_pattern => $replacement) {
foreach ($xp->query($search_pattern) as $node) {
$node->nodeValue = $replacement;
}
}
}
The problem is that now I need to do different "search/replace" on different parts of the XML dom. I had hoped something like the following would work, but DOMXPath can't use DOMDocumentFragment :(
The first part (until the foreach loop) of the example below works like a charm. I'm looking for inspiration for an alternative way to go around it which is still short and readable (without to much boiler plate).
Code:
<?php
$dom = new DOMDocument;
$dom->loadXml(file_get_contents('container.xml'));
$payload = $dom->getElementsByTagName('Payload')->item(0);
xml_search_replace($dom, array('//MessageReference' => 'SRV4-ID00000000001'));
$payloadXmlTemplate = file_get_contents('payload_template.xml');
foreach (array(array('id' => 'some_id_1'),
array('id' => 'some_id_2')) as $request) {
$fragment = $dom->createDocumentFragment();
$fragment->appendXML($payloadXmlTemplate);
xml_search_replace($fragment, array('//PayloadElement' => $request['id']));
$payload->appendChild($fragment);
}

Answer 1

Thanks to Francis Avila I came up with the following:
<?php
function xml_search_replace($node, $search_replace_rules) {
if (!is_array($search_replace_rules)) {
return;
}
$xp = new DOMXPath($node->ownerDocument);
foreach ($search_replace_rules as $search_pattern => $replacement) {
foreach ($xp->query($search_pattern, $node) as $matchingNode) {
$matchingNode->nodeValue = $replacement;
}
}
}
$dom = new DOMDocument;
$dom->loadXml(file_get_contents('container.xml'));
$payload = $dom->getElementsByTagName('Payload')->item(0);
xml_search_replace($dom->documentElement, array('//MessageReference' => 'SRV4-ID00000000001'));
$payloadXmlTemplate = file_get_contents('payload_template.xml');
foreach (array(array('id' => 'some_id_1'),
array('id' => 'some_id_2')) as $request) {
$fragment = $dom->createDocumentFragment();
$fragment->appendXML($payloadXmlTemplate);
xml_search_replace($payload->appendChild($fragment),
array('//PayloadElement' => $request['id']));
}