(PHP 5 >= 5.3.0, PHP 7, PHP 8)
DOMXPath::registerPhpFunctions — Register PHP functions as XPath functions
This method enables the ability to use PHP functions within XPath expressions.
No value is returned.
The following examples use book.xml which contains the following:
Example #1 book.xml
<?xml version="1.0" encoding="UTF-8"?> <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>
Example #2 DOMXPath::registerPHPFunctions() with php:functionString
<?php
$doc = new DOMDocument;
$doc->load('book.xml');
$xpath = new DOMXPath($doc);
// Register the php: namespace (required)
$xpath->registerNamespace("php", "http://php.net/xpath");
// Register PHP functions (no restrictions)
$xpath->registerPHPFunctions();
// Call substr function on the book title
$nodes = $xpath->query('//book[php:functionString("substr", title, 0, 3) = "PHP"]');
echo "Found {$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
Example #3 DOMXPath::registerPHPFunctions() with php:function
<?php
$doc = new DOMDocument;
$doc->load('book.xml');
$xpath = new DOMXPath($doc);
// Register the php: namespace (required)
$xpath->registerNamespace("php", "http://php.net/xpath");
// Register PHP functions (has_multiple only)
$xpath->registerPHPFunctions("has_multiple");
function has_multiple($nodes) {
// Return true if more than one author
return count($nodes) > 1;
}
// Filter books with multiple authors
$books = $xpath->query('//book[php:function("has_multiple", author)]');
echo "Books with multiple authors:\n";
foreach ($books as $book) {
echo $book->getElementsByTagName("title")->item(0)->nodeValue . "\n";
}
?>The above example will output something similar to:
Books with multiple authors: PHP Basics