The DOMXPath::query() function is an inbuilt function in PHP which is used to evaluate the given XPath expression.
Syntax:
DOMNodeList DOMXPath::query( string $expression,
DOMNode $contextnode, bool $registerNodeNS )
Parameters: This function accept three parameters as mentioned above and described below:
- $expression: It specifies the XPath expression to execute.
- $contextnode (Optional): It specifies the optional contextnode for doing relative XPath queries. By default, the queries are relative to the root element.
- $registerNodeNS (Optional): It specifies the optional registerNodeNS to disable automatic registration of the context node.
Return Value: This function returns a DOMNodeList containing all nodes matching the given XPath expression. Any expression which does not return nodes will return an empty DOMNodeList.
Below given programs illustrate the DOMXPath::query() function in PHP:
Program 1: In this program we will fetch all the element values of elements with name content.
<?php // Create a new DOMDocument instance $document = new DOMDocument(); // Create a XML $xml = <<<XML <?xml version="1.0" encoding="utf-8"?> <root> <content> First </content> <content> Second </content> <content> Third </content> </root> XML; // Load the XML $document->loadXML($xml); // Create a new DOMXPath instance $xpath = new DOMXPath($document); // Get the root element $tbody = $document->getElementsByTagName('root')->item(0); // Get all the element with name content $query = '//content'; // Execute the query $entries = $xpath->query($query); foreach ($entries as $entry) { echo $entry->nodeValue . "<br>"; } ?> |
Output:
First Second Third
Program 2: In this program we will count all the elements with name h1.
<?php // Create a new DOMDocument instance $document = new DOMDocument(); // Create a XML $xml = <<<XML <?xml version="1.0" encoding="utf-8"?> <root> <h1> Hello </h1> <h1> World </h1> <h1> Foo </h1> <h1> Bar </h1> </root> XML; // Load the XML $document->loadXML($xml); // Create a new DOMXPath instance $xpath = new DOMXPath($document); // Get the root element $tbody = $document->getElementsByTagName('root')->item(0); // Get all the element with name h1 $query = '//h1'; // Execute the query $entries = $xpath->query($query); // Count the number of headings echo count($entries); ?> |
Output:
4
