PHP: Find XML node and insert child - php

Question

I have an xml document with the following structure:
<?xml version="1.0" encoding="UTF-8"?>
<items>
<item>
<id>1</id>
<url>www.test.com</url>
</item>
<item>
<id>2</id>
<url>www.test2.com</url>
</item>
</items>
I would like to be able to search for a node value, such as the value of 1 for the id field. Then, once that node is found, select the parent node, which would be < item > and insert a new child within.
I know the concept of using dom document, but not sure how to do it in this instance.

Answer 1

This should be a start:
$dom = new DOMDocument;
$dom->loadXML($input);
$ids = $dom->getElementsByTagName('id');
foreach ($ids as $id) {
if ($id->nodeValue == '1') {
$child = $dom->createElement('tagname');
$child->appendChild($dom->createTextNode('some text'));
$id->parentNode->appendChild($child);
}
}
$xml = $dom->saveXML();
or something close to it.

Answer 2

You can do the same thing in a simpler way. Instead of looking for an <id/> node whose value is 1 then selecting its parent, you can reverse the relation and look for any node which has an <id/> child whose value is 1.
You can do that very easily in XPath, and here's how to do it in SimpleXML:
$items = simplexml_load_string(
'<?xml version="1.0" encoding="UTF-8"?>
<items>
<item>
<id>1</id>
<url>www.test.com</url>
</item>
<item>
<id>2</id>
<url>www.test2.com</url>
</item>
</items>'
);
$nodes = $items->xpath('*[id = "1"]');
$nodes[0]->addChild('new', 'value');
echo $items->asXML();