Last updated: Sat, 24 Mar 2007

DOMXPath->query()

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DOMXPath->query() — Evaluates the given XPath expression

Popis

class DOMXPath {
DOMNodeList query ( string $expression [, DOMNode $contextnode] )
}

Executes the given XPath expression.

Seznam parametrů

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.

Návratové hodnoty

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

Příklady

Příklad 417. 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 starts 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";

}

?>

Výše uvedený příklad vypíše:


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";

}

?>

Viz také

DOMXPath->evaluate()

DOMXPath->registerNamespace()

DOMXPath->evaluate()

Last updated: Sat, 24 Mar 2007

add a note User Contributed Notes
DOMXPath->query()

Hayley Watson
12-Aug-2007 05:43


Note that if your DOMDocument was loaded from HTML, where element and attribute names are case-insensitive, the DOM parser converts them all to lower-case, so your XPath queries will have to as well; '//A/@HREF' won't find anything even if the original HTML contained "<A HREF='example.com'>".

nicolas_rainardNOSPAM at yahoo dot fr
10-Jul-2007 02:04


Please note that what clochix says is valid for *any* document which has a default namespace (as it is the case for XHTML).



This document :



<?xml version="1.0" encoding="UTF-8" ?>



<root xmlns="http://www.exemple.org/namespace">



    <element id="1">

    ...

    </element>



    <element id="2">

    ...

    </element>



</element>



must be accessed this way :



$document = new DOMDocument();

$document->load('document.xml');



$xpath = new DOMXPath($document);

$xpath->registerNameSpace('fakeprefix', 'http://www.exemple.org/namespace');



$elements = $xpath->query('//fakeprefix:element');



Of course, there is no prefix in the original document, but the DOMXPath class *needs* one, whatever it is, if you use a default namespace. It *doesn't work* if you specify an empty prefix like this :



$xpath->registerNameSpace('', 'http://www.exemple.org/namespace');



Hope this help to spare some time...

clochix at clochix dot net
01-Mar-2007 04:05


If you want to perform queries on XHTML documents, you must fix a default namespace:



$doc = new DOMDocument;

$doc->preserveWhiteSpace = true;

$doc->resolveExternals = true; // for character entities

$doc->load("http://www.w3.org/");

$xpath = new DOMXPath($doc);

// won't work

$entries = $xpath->query("//div");

// you should use :

$xpath->registerNamespace("html", "http://www.w3.org/1999/xhtml");

$entries = $xpath->query("//html:div");

ckrack at i-z dot de
22-Dec-2005 07:27


tried finding a node by it's text content?



// Get all elements that equal the string "test"

$query = "//*[.='test']";

jakob dot voss at nichtich dot de
14-Nov-2005 12:33


You can transform the result nodes into new DOMDocument objects this way:



<?php

$result = $xpath->query($query);

$resultNode = $result->item(0);

$newDom = new DOMDocument;

$newDom->appendChild($newDom->importNode($resultNode,1));



print "<pre>" . htmlspecialchars($newDom->saveXML()) . "</pre>";

?>

Eric Hanson
12-Jul-2005 05:40


Two great XPath references follow.



XPath in Five Paragraphs (finally!):

http://www.rpbourret.com/xml/XPathIn5.htm



The w3c spec actually has a bunch of helpful examples:

http://www.w3.org/TR/xpath#location-paths

add a note

DOMXPath->registerNamespace()

DOMXPath->evaluate()

Last updated: Sat, 24 Mar 2007