RE: Dynamic Sorting

The usual solution, which covers simple cases, is

<xsl:sort select="*[name()=$sortkey]"/>

For more complex cases you need to either (a) use xx:evaluate(), or (b)
generate or modify the stylesheet source before its compiled.

Michael Kay
Software AG
home: Michael.H.Kay@xxxxxxxxxxxx
work: Michael.Kay@xxxxxxxxxxxxxx 

> -----Original Message-----
> From: owner-xsl-list@xxxxxxxxxxxxxxxxxxxxxx 
> [mailto:owner-xsl-list@xxxxxxxxxxxxxxxxxxxxxx] On Behalf Of 
> Ben Macaulay
> Sent: 07 November 2002 19:34
> To: XSL-List@xxxxxxxxxxxxxxxxxxxxxx
> Subject:  Dynamic Sorting
> 
> 
> Question -> Can you define a template that allows you to 
> define, at runtime, the elements that you want to sort on?  
> For instance, we have an XML document as follows.
> 
>     <records>
>         <contact id="0001">
>             <title>Mr</title>
>             <forename>John</forename>
>             <surname>Smith</surname>
>         </contact>
>         <contact id="0002">
>             <title>Dr</title>
>             <forename>Amy</forename>
>             <surname>Jones</surname>
>         </contact>
>         ...
>     <records>
> 
> What we want to do is sort by (surname, forename), or sort by 
> (title, surname), or whatever we decide on the day.  In our 
> XSL, we would like to be able to specify variables that 
> dictate how the sorting should be done.  For instance, 
> consider the following XSL extract.
> 
>     <xsl:variable name="sort-by-element-1" value="surname" />
>     <xsl:variable name="sort-by-element-2" value="forename" />
> 
> In reality we are not going to hard code the variable values 
> like this, but rather pull them in from another document by 
> way of the document() function, but that's not important right now.
> 
> The problem is, later on in the XSL we can't have <xsl:sort 
> select="{$sort-by-element-1}" /> since xsl:sort's select 
> attribute doesn't accept attribute value templates.  You can 
> specify attribute value templates for xsl:sort's other 
> attributes, for instance the article at 
> http://www.biglist.com/lists/xsl-list/archives/200012/msg00392
.html
demonstrates how to dynamically specify a descending or ascending sort
order.  However you can't do this for the select attribute.  Short of
creating nonportable XSL by using saxon:evaluate() or xalan:evaluate() I
can't see a way around this.  Any suggestions?  Can this kind of dynamic
sorting be done at all?


Cheers,
Ben Macaulay
Senior Software Engineer
DHL Worldwide Express

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