DOMXPath::query
Evaluates the given XPath expression
Description
public mixed DOMXPath::query(string $expression, DOMNodenull $contextNode = null, bool $registerNodeNS = true)
Parameters
-
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
-
Whether to automatically register the in-scope namespace prefixes of the context node to the DOMXPath object.
This can be used to avoid needing to call DOMXPath::registerNamespace manually for each in-scope namespaces.
When a namespace prefix conflict exists, only the nearest descendant namespace prefix is registered.
Return Values
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.
Examples
Example #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 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";
}
?>
The above example will output:
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";
}
?>