(PHP >= 8.4.0)
DOMXPath::registerPhpFunctionNS — Register a PHP functions as namespaced XPath function
$namespaceURI, string $name, callable $callable): voidThis method enables the ability to use a PHP function as a namespaced XPath function inside XPath expressions.
namespaceURInamecallableNo value is returned.
Example #1 Register a namespaced XPath function and call it from the XPath expression
<?php
$xml = <<<EOB
<books>
<book>
<title>PHP Basics</title>
<author>Jim Smith</author>
<author>Jane Smith</author>
</book>
<book>
<title>PHP Secrets</title>
<author>Jenny Smythe</author>
</book>
<book>
<title>XML basics</title>
<author>Joe Black</author>
</book>
</books>
EOB;
$doc = new DOMDocument;
$doc->loadXML($xml);
$xpath = new DOMXPath($doc);
// Register the my: namespace (required)
$xpath->registerNamespace("my", "urn:my.ns");
// Register PHP functions (no restrictions)
$xpath->registerPHPFunctionNS(
'urn:my.ns',
'substring',
fn (array $arg1, int $start, int $length) => substr($arg1[0]->textContent, $start, $length)
);
// Call substr function on the book title
$nodes = $xpath->query('//book[my:substring(title, 0, 3) = "PHP"]');
echo "Found {$nodes->length} books starting with 'PHP':\n";
foreach ($nodes as $node) {
$title = $node->getElementsByTagName("title")->item(0)->nodeValue;
$author = $node->getElementsByTagName("author")->item(0)->nodeValue;
echo "$title by $author\n";
}
?>The above example will output something similar to:
Found 2 books starting with 'PHP': PHP Basics by Jim Smith PHP Secrets by Jenny Smythe