libxml offers a number of functions for handling errors, which can be employed to capture and deal with errors in XSLT processing.
Example #1 fruits.xml
A valid XML file.
<fruits> <fruit>Apple</fruit> <fruit>Banana</fruit> <fruit>Cherry</fruit> </fruits>
Example #2 fruits.xsl
Contains an invalid select expression.
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:output method="html" encoding="utf-8" indent="no"/> <xsl:template match="fruits"> <ul> <xsl:apply-templates/> </ul> </xsl:template> <xsl:template match="fruit"> <li><xsl:value-of select="THIS IS A DELIBERATE ERROR!"/></li> </xsl:template> </xsl:stylesheet>
Example #3 Collating and printing errors
The example below captures and displays libxml errors raised when calling XSLTProcessor::importStyleSheet() with a stylesheet containing an error.
<?php
$xmldoc = new DOMDocument();
$xsldoc = new DOMDocument();
$xsl = new XSLTProcessor();
$xmldoc->loadXML('fruits.xml');
$xsldoc->loadXML('fruits.xsl');
libxml_use_internal_errors(true);
$result = $xsl->importStyleSheet($xsldoc);
if (!$result) {
foreach (libxml_get_errors() as $error) {
echo "Libxml error: {$error->message}\n";
}
}
libxml_use_internal_errors(false);
if ($result) {
echo $xsl->transformToXML($xmldoc);
}
?>The above example will output something similar to:
Libxml error: Invalid expression Libxml error: compilation error: file fruits.xsl line 9 element value-of Libxml error: xsl:value-of : could not compile select expression 'THIS IS A DELIBERATE ERROR!'