Dynamic Sorting - Using a variable to determine the so

Hi - I'm trying to dynamically sort a list based on the value of an element
in my xml document.  Ideally, I'd be able to pass this value to the xsl:sort
element in the xsl document to determine the sort criteria.  In the example
below, "sortby" could have the value "name" or "age".

Here's the XML:

<root>
	<sortby>name</sortby>
	<data>
		<person><name>Bob</name><age>21</age></person>
		<person><name>Jim</name><age>63</age></person>
		<person><name>Gus</name><age>55</age></person>
		<person><name>Van</name><age>18</age></person>
		<person><name>Sam</name><age>32</age></person>
		<person><name>Don</name><age>39</age></person>
		<person><name>Ron</name><age>33</age></person>
	</data>
</root>


And here's the XSL I tried (it doesn't work, but you'll see what I'm trying
to do).  I also tried curly braces in the xsl:sort select tag to evaluate
the sortexpression string as an expression, but no luck.  I understand
that's not the intended use of the curly brackets, but gave it a shot.


<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

<xsl:output method="html" indent="no"/>

<xsl:template match="/">
	<xsl:apply-templates/>
</xsl:template>

<xsl:template match="root">
	<xsl:apply-templates select="data">
		<xsl:with-param name="sortexpression" select="sortby"/>
	</xsl:apply-templates>
</xsl:template>

<xsl:template match="data">
	<xsl:param name="sortexpression"/>
	<xsl:apply-templates select="person">
		<xsl:sort select="$sortexpression"/>
	</xsl:apply-templates>
</xsl:template>

<xsl:template match="person">
	<xsl:value-of select="name"/>
	<xsl:text>, </xsl:text>
	<xsl:value-of select="age"/>
	<br />
</xsl:template>

</xsl:stylesheet>


If I can't do this, I find I have to write a bunch of xsl:if clauses and
that solution doesn't scale and results in bulky code.

Thanks ahead of time for your thoughts.

Mark Swardstrom
Nimble Technology


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