DOMXPath->query()

Evaluates the given XPath expression ()

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 489. 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";
}
?>