DOMXPath::query

(PHP 5, PHP 7)

DOMXPath::query — Evaluates the given XPath expression

Description

public DOMXPath::query ( string $expression [, DOMNode $contextnode [, bool $registerNodeNS = true ]] ) : DOMNodeList

Executes the given XPath expression.

Parameters

expression

The XPath expression to execute.

contextnode

The optional contextnode can be specified for doing relative XPath queries. By default, the queries are relative to the root element.

registerNodeNS

The optional registerNodeNS can be specified to disable automatic registration of the context node.

Return Values

Returns a DOMNodeList containing all nodes matching the given XPath expression. Any expression which does not return nodes will return an empty DOMNodeList.

If the expression is malformed or the contextnode is invalid, DOMXPath::query() returns false.

Examples

Example #1 Getting all the english books

<?php

$doc = new DOMDocument;

// We don't want to bother with white spaces
$doc->preserveWhiteSpace = false;

$doc->load('book.xml');

$xpath = new DOMXPath($doc);

// We start from the root element
$query = '//book/chapter/para/informaltable/tgroup/tbody/row/entry[. = "en"]';

$entries = $xpath->query($query);

foreach ($entries as $entry) {
    echo "Found {$entry->previousSibling->previousSibling->nodeValue}," .
         " by {$entry->previousSibling->nodeValue}\n";
}
?>

The above example will output:

Found The Grapes of Wrath, by John Steinbeck
Found The Pearl, by John Steinbeck

We can also use the contextnode parameter to shorten our expression: 

<?php

$doc = new DOMDocument;
$doc->preserveWhiteSpace = false;

$doc->load('book.xml');

$xpath = new DOMXPath($doc);

$tbody = $doc->getElementsByTagName('tbody')->item(0);

// our query is relative to the tbody node
$query = 'row/entry[. = "en"]';

$entries = $xpath->query($query, $tbody);

foreach ($entries as $entry) {
    echo "Found {$entry->previousSibling->previousSibling->nodeValue}," .
         " by {$entry->previousSibling->nodeValue}\n";
}
?>

See Also

  • DOMXPath::evaluate() - Evaluates the given XPath expression and returns a typed result if possible

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Licensed under the Creative Commons Attribution License v3.0 or later.
https://www.php.net/manual/en/domxpath.query.php