XSLT 1.0 Sort Items

Question

I have the following XML document:

<?xml version="1.0" encoding="UTF-8"?> <objects> <object>Clutch</object> <object>Gearbox</object> <object>Cylinder head</object> <object>Starter</object> <object>Airbox</object> <object>Inlet manifold</object> </objects> 

And the following XSLT document:

 <?xml version="1.0" encoding="UTF-8"?> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:output method="xml" indent="yes"/> <xsl:template match="objects"> <parts> <xsl:apply-templates> <xsl:sort select="object"/> </xsl:apply-templates> </parts> </xsl:template> <xsl:template match="object"> <part> <xsl:apply-templates/> </part> </xsl:template> </xsl:stylesheet> 

When applied, I get the following output as expected, but it does not sort:

 <?xml version="1.0" encoding="UTF-8"?> <parts> <part>Clutch</part> <part>Gearbox</part> <part>Cylinder head</part> <part>Starter</part> <part>Airbox</part> <part>Inlet manifold</part> </parts> 

Why is <xsl:sort select="object"/> not applied?

Answer 1

The reason is here:

  <parts> <xsl:apply-templates> <xsl:sort select="object"/> </xsl:apply-templates> </parts> 

This applies the patterns to the children ( object ) of the current node ( objects ) and sorts them by the string value of their first child element.

However, in the provided XML document, the object does not have any child elements of the object , so they all have the same sort key - an empty string - and their original order does not change the sort.

Decision

  <parts> <xsl:apply-templates> <xsl:sort select="."/> </xsl:apply-templates> </parts> 

Full conversion becomes :

 <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:output method="xml" omit-xml-declaration="yes" indent="yes"/> <xsl:strip-space elements="*"/> <xsl:template match="objects"> <parts> <xsl:apply-templates> <xsl:sort select="."/> </xsl:apply-templates> </parts> </xsl:template> <xsl:template match="object"> <part> <xsl:apply-templates/> </part> </xsl:template> </xsl:stylesheet> 

and when it applies to the provided XML document:

 <objects> <object>Clutch</object> <object>Gearbox</object> <object>Cylinder head</object> <object>Starter</object> <object>Airbox</object> <object>Inlet manifold</object> </objects> 

the desired, correct result is output:

 <parts> <part>Airbox</part> <part>Clutch</part> <part>Cylinder head</part> <part>Gearbox</part> <part>Inlet manifold</part> <part>Starter</part> </parts>