DOMXPath::query

(PHP 5, PHP 7, PHP 8)

DOMXPath::query Evaluates the given XPath expression

Опис

public DOMXPath::query(string $expression, ?DOMNode $contextNode = null, bool $registerNodeNS = true): mixed

Executes the given XPath expression.

Параметри

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

Визначає, чи необхідно автоматично реєструвати префікси простору імен в області видимості контекстного вузла для об'єкта DOMXPath. Потрібно для того, щоб не викликати метод DOMXPath::registerNamespace() для кожного простору імен в області видимості. Коли префікси збігаються, реєструється тільки префікс простору імен найближчого нащадка.

Значення, що повертаються

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.

Помилки/виключення

The following errors are possible when using an expression that invokes PHP callbacks.

  • Throws an Error if a PHP callback is invoked but there were no callbacks registered, or if the named callback was not registered.
  • Throws a TypeError if the php:function syntax is used and the handler name is not a string.
  • Throws an Error if a non-DOM object was returned from a callback.

Приклади

Приклад #1 Getting all the english books

<?php

$doc
= new DOMDocument;

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

$doc->load('examples/book-docbook.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";
}
?>

Поданий вище приклад виведе:

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('examples/book-docbook.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";
}
?>

Прогляньте також

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