(PHP 5, PHP 7)
DOMXPath::query — Evaluates the given XPath expression
$expression
[, DOMNode $contextnode
[, bool $registerNodeNS = TRUE
]] ) : DOMNodeList
Executes the given XPath expression.
expressionThe 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.
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.
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";
}
?>
以上例程会输出：
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";
}
?>