DOMXPath::query
Evaluates the given XPath expression
Beschreibung
public DOMNodeList DOMXPath::query
( string $expression
[, DOMNode $contextnode
[, bool $registerNodeNS = true
]] )
Parameter-Liste
-
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.
Rückgabewerte
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.
Beispiele
Beispiel #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";
}
?>
Das oben gezeigte Beispiel erzeugt folgende
Ausgabe:
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";
}
?>