Php/docs/domxpath.query
DOMXPath::query
(PHP 5, PHP 7)
DOMXPath::query — Evaluates the given XPath expression
说明
public DOMXPath::query
( string $expression
[, DOMNode $contextnode
[, bool $registerNodeNS = true
]] ) : DOMNodeList
Executes the given XPath expression.
参数
expression- The XPath expression to execute.
contextnode- The optional
contextnodecan be specified for doing relative XPath queries. By default, the queries are relative to the root element. registerNodeNS- The optional
registerNodeNScan be specified to disable automatic registration of the context node.
返回值
Returns a DOMNodeList containing all nodes matching
the given XPath expression. Any expression which
does not return nodes will return an empty
DOMNodeList.
If the expression is malformed or the
contextnode is invalid,
DOMXPath::query() returns false.
范例
Example #1 Getting all the english books
<?php$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";}?>
参见
- DOMXPath::evaluate() - Evaluates the given XPath expression and returns a typed result if possible
