DOMXPath::registerPhpFunctions
(PHP 5 >= 5.3.0, PHP 7, PHP 8)
DOMXPath::registerPhpFunctions — Register PHP functions as XPath functions
Description
public DOMXPath::registerPhpFunctions(string|array|null $restrict = null): void
This method enables the ability to use PHP functions within XPath expressions.
Parameters
-
restrict
-
Use this parameter to only allow certain functions to be called from XPath.
This parameter can be either a string (a function name) or an array of function names.
Return Values
No value is returned.
Examples
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
See Also
- DOMXPath::registerNamespace() - Registers the namespace with the DOMXPath object
- DOMXPath::query() - Evaluates the given XPath expression
- DOMXPath::evaluate() - Evaluates the given XPath expression and returns a typed result if possible
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https://www.php.net/manual/en/domxpath.registerphpfunctions.php