[xsl] Re: How can I sort values that have been calculated dynamically?

Subject: [xsl] Re: How can I sort values that have been calculated dynamically?
From: Dimitre Novatchev <dnovatchev@xxxxxxxxx>
Date: Fri, 13 Jul 2001 03:58:37 -0700 (PDT)
Bryan Tulloch wrote:


> The problem:
> Some of the columns contain data that is not directly in the source XML but
> is computed from it (eg there is a column containing the total number of
> unique Case_Code elements for each unique User_Name).  I have a template
> matching each unique User_Name, and within this the data is being output
> into the table using this code:
>      <TH>
> 	<xsl:variable name="ThisUser" select="." />
>      <xsl:value-of
> select="count(//User[./User_Name=$ThisUser][not(Case_Code=preceding::Case_Co
> de)])" />
>      </TH>
>  however, I have not been able to code the column heading so that it sorts
> by this column when clicked.
> Any suggestions as to how to go about this?

Hi Bryan,

In case the value to act as a sort key is difficult to express as a single
expression, then one solution is to create a new node-set which contains these
calculated values (typically as sub-elements or attributes) and then to sort this
last node-set.

This solution is both time- and space-consuming.

The better alternative is to use the generic sort() template


which accepts as a parameter a template reference to a custom template that will
implement "comparison" between two nodes.

The comparisons that may be implemented within a custom template are not limited to
the requirement that a sort key must be expressed as a single expression.

The results of using a generic template in general and the sort() generic template
in this particular case are:

 -- increased flexibility
 -- ability to solve efficiently a larger set of problems.
 -- reduced complexity (the user produces only the custom template(s), the generic
template stays the same and is never changed.
 -- higher reusability and reliability.
 -- reduced chances for errors.
 -- considerable savings of programming time.

Dimitre Novatchev.

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