PHP : Function Reference : DOM Functions : DOMXPath->query() PHP Examples Tutorials References

Example 545. 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";

}
?>

The above example will output:

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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:

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<?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";

}
?>

Code Examples / Notes » dom_domxpath_query

Unfortunately PHP's DOM extension doesn't support use of: <?xml-stylesheet type="text/xsl" ... ?> processing instruction. Here is an example, how to implement it using XPath query and extending DOMDocument by a method output(). <?php // This simple function adds missing direct usage of anonymous instances // in PHP5's reference model function a($var) { return $var; } // Extended DOMDocument class class MyDOMDocument extends DOMDocument { public function output() { $stylesheets = array(); $PIs = a(new DOMXPath($this)) ->query('/processing-instruction("xml-stylesheet")'); foreach($PIs as $PI) { // This might be implemented cleaner by regular parsing // of DOMProcessingInstruction::data property if(ereg('type *= *"text/xsl" +href *= *"([^"]+)"', $PI->data, $mem)) { // Here should be verified, that XSL file exists. a($stylesheets[] = new DOMDocument())->load($mem[1]); } } if($stylesheets) { $processor = new XSLTProcessor(); foreach($stylesheets as $stylesheet) $processor->importStylesheet($stylesheet); return $processor->transformToDoc($this); } // If no stylesheet instructions present, return self directly else return $this; } } ?> Usage: <?php $document = new MyDOMDocument(); $document->load('my.xml'); echo $document->output()->saveXML(); ?> With following file my.xml: <?xml version="1.0" ?> <?xml-stylesheet type="text/xsl" href="my.xsl" ?> <my-root /> and existing file my.xsl that code will transform the xml file using my.xsl and output the result.

The order of nodes in the return value is not guaranteed. When my code was on an old server, the returned DOMNodeList was in document order. On the new server, the returned DOMNodeList is in a consistent order, but it is not in document order. PHP passes this function call off to the xmlXPathEvalExpression() function in libxml. That function in libxml only accepts two arguments - the same two this PHP function accepts. There must have been a change in the libxml version from the old server to the new server, and that libxml behaves differently. This would be okay if PHP had a way to compare nodes so I can resort the nodes manually, but there is not. So, there is no guaranteed way to get an ordered list of nodes like DOM 3 XPath provides.

Please note that what clochix says is valid for *any* document which has a default namespace (as it is the case for XHTML). This document : <?xml version="1.0" encoding="UTF-8" ?> <root xmlns="http://www.exemple.org/namespace"> <element id="1"> ... </element> <element id="2"> ... </element> </element> must be accessed this way : $document = new DOMDocument(); $document->load('document.xml'); $xpath = new DOMXPath($document); $xpath->registerNameSpace('fakeprefix', 'http://www.exemple.org/namespace'); $elements = $xpath->query('//fakeprefix:element'); Of course, there is no prefix in the original document, but the DOMXPath class *needs* one, whatever it is, if you use a default namespace. It *doesn't work* if you specify an empty prefix like this : $xpath->registerNameSpace('', 'http://www.exemple.org/namespace'); Hope this help to spare some time...

If you want to perform queries on XHTML documents, you must fix a default namespace: $doc = new DOMDocument; $doc->preserveWhiteSpace = true; $doc->resolveExternals = true; // for character entities $doc->load("http://www.w3.org/"); $xpath = new DOMXPath($doc); // won't work $entries = $xpath->query("//div"); // you should use : $xpath->registerNamespace("html", "http://www.w3.org/1999/xhtml"); $entries = $xpath->query("//html:div");

DOMXPath->query()

Evaluates the given XPath expression ()

Example 545. Getting all the english books

Code Examples / Notes » dom_domxpath_query

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