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DOMXPath->query()

(no version information, might be only in CVS)

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

说明

class DOMXPath {

DOMNodeList query ( string expression [, DOMNode contextnode] )

}

Executes the given XPath expression.

参数

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.

返回值

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

范例

例子 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 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";
}
?>

上例将输出：

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";
}
?>

参见

DOMXPath->evaluate()


add a note add a note User Contributed Notes
Colin
07-Jul-2006 06:09
The documents do not specify it, but query (I'm using 5.0.5) will return FALSE on error.  Such an error would be a malformed query (not the same as a query with no matches).
ckrack at i-z dot de
23-Dec-2005 11:27
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 04:33
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
13-Jul-2005 08:40
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
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