xslt_process

Description

The xslt_process() function is the crux of the new XSLT extension. It allows you to perform an XSLT transformation using almost any type of input source - the containers. This is accomplished through the use of argument buffers -- a concept taken from the Sablotron XSLT processor (currently the only XSLT processor this extension supports). The input containers default to a filename 'containing' the document to be processed. The result container defaults to a filename for the transformed document. If the result container is not specified - i.e. NULL - than the result is returned.

Containers can also be set via the $arguments array (see below).

The simplest type of transformation with the xslt_process() function is the transformation of an XML file with an XSLT file, placing the result in a third file containing the new XML (or HTML) document. Doing this with sablotron is really quite easy...

<?php

// Allocate a new XSLT processor
$xh = xslt_create();

// Process the document
if (xslt_process($xh, 'sample.xml', 'sample.xsl', 'result.xml')) {
    print "SUCCESS, sample.xml was transformed by sample.xsl into result.xml";
    print ", result.xml has the following contents\n<br>\n";
    print "<pre>\n";
    readfile('result.xml');
    print "</pre>\n";
}
else {
    print "Sorry, sample.xml could not be transformed by sample.xsl into";
    print "  result.xml the reason is that " . xslt_error($xh) . " and the ";
    print "error code is " . xslt_errno($xh);
}

xslt_free($xh);

 ?>

While this functionality is great, many times, especially in a web environment, you want to be able to print out your results directly. Therefore, if you omit the third argument to the xslt_process() function (or provide a NULL value for the argument), it will automatically return the value of the XSLT transformation, instead of writing it to a file...

Example 2. Using the xslt_process() to transform an XML file and a XSL file to a variable containing the resulting XML data <?php // Allocate a new XSLT processor $xh = xslt_create(); // Process the document, returning the result into the $result variable $result = xslt_process($xh, 'sample.xml', 'sample.xsl'); if ($result) { print "SUCCESS, sample.xml was transformed by sample.xsl into the \$result"; print " variable, the \$result variable has the following contents\n<br>\n"; print "<pre>\n"; print $result; print "</pre>\n"; } else { print "Sorry, sample.xml could not be transformed by sample.xsl into"; print " the \$result variable the reason is that " . xslt_error($xh) . print " and the error code is " . xslt_errno($xh); } xslt_free($xh); ?>

The above two cases are the two simplest cases there are when it comes to XSLT transformation and I'd dare say that they are the most common cases, however, sometimes you get your XML and XSLT code from external sources, such as a database or a socket. In these cases you'll have the XML and/or XSLT data in a variable -- and in production applications the overhead of dumping these to file may be too much. This is where XSLT's "argument" syntax, comes to the rescue. Instead of files as the XML and XSLT arguments to the xslt_process() function, you can specify "argument place holders" which are then subsituted by values given in the arguments array (5th parameter to the xslt_process() function). The following is an example of processing XML and XSLT into a result variable without the use of files at all.

Example 3. Using the xslt_process() to transform a variable containing XML data and a variable containing XSL data into a variable containing the resulting XML data <?php // $xml and $xsl contain the XML and XSL data $arguments = array( '/_xml' => $xml, '/_xsl' => $xsl ); // Allocate a new XSLT processor $xh = xslt_create(); // Process the document $result = xslt_process($xh, 'arg:/_xml', 'arg:/_xsl', NULL, $arguments); if ($result) { print "SUCCESS, sample.xml was transformed by sample.xsl into the \$result"; print " variable, the \$result variable has the following contents\n<br>\n"; print "<pre>\n"; print $result; print "</pre>\n"; } else { print "Sorry, sample.xml could not be transformed by sample.xsl into"; print " the \$result variable the reason is that " . xslt_error($xh) . print " and the error code is " . xslt_errno($xh); } xslt_free($xh); ?>

Finally, the last argument to the xslt_process() function represents an array for any top-level parameters that you want to pass to the XSLT document. These parameters can then be accessed within your XSL files using the <xsl:param name="parameter_name"> instruction. The parameters must be UTF-8 encoded and their values will be interpreted as strings by the Sablotron processor. In other words - you cannot pass node-sets as parameters to the XSLT document.