[xsl] Using the f:xsltSort() function of FXSL for dynamic sorting (Was: Re: [xsl] Dynamically define number of xsl:sort stmts using parameters)

Subject: [xsl] Using the f:xsltSort() function of FXSL for dynamic sorting (Was: Re: [xsl] Dynamically define number of xsl:sort stmts using parameters)
From: "Dimitre Novatchev" <dnovatchev@xxxxxxxxx>
Date: Wed, 28 Mar 2007 22:46:59 -0700
Here's how one can use the FXSL function

f:xsltSort()

This transformation:

<xsl:stylesheet version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
xmlns:xs="http://www.w3.org/2001/XMLSchema";
xmlns:f="http://fxsl.sf.net/";
exclude-result-prefixes="xs f"


<xsl:import href="../f/func-map.xsl"/> <xsl:import href="../f/func-flip.xsl"/> <xsl:import href="../f/func-standardXSLTXpathFunctions.xsl"/> <xsl:import href="../f/func-standardAxisXpathFunctions.xsl"/>

<!--
 To be applied on testFunc-xsltSort2.xml
-->

<xsl:output omit-xml-declaration="yes" indent="yes"/>

<xsl:template match="/">
 <employees>
  <xsl:sequence select=
    "f:xsltSort(/*/employee,
                      f:map(f:flip(f:element()), /*/sort)
                     )"/>
 </employees>
</xsl:template>
</xsl:stylesheet>

when applied on this source xml document:

<employees>
 <employee hireDate="04/23/1999">
   <last>Hill</last>
   <first>Phil</first>
   <salary>089000</salary>
 </employee>

 <employee hireDate="09/01/1998">
   <last>Herbert</last>
   <first>Johnny</first>
   <salary>095000</salary>
 </employee>

 <employee hireDate="08/20/2000">
   <last>Hill</last>
   <first>Graham</first>
   <salary>100000</salary>
 </employee>



 <sort order="1">last</sort>
 <sort order="3">salary</sort>
 <sort order="3">first</sort>
</employees>

produces the wanted result:

<employees>
  <employee hireDate="09/01/1998">
     <last>Herbert</last>
     <first>Johnny</first>
     <salary>095000</salary>
 </employee>
  <employee hireDate="04/23/1999">
     <last>Hill</last>
     <first>Phil</first>
     <salary>089000</salary>
 </employee>
  <employee hireDate="08/20/2000">
     <last>Hill</last>
     <first>Graham</first>
     <salary>100000</salary>
 </employee>
</employees>


Here is the code of the function f:xsltSort():


<xsl:stylesheet version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
xmlns:xs="http://www.w3.org/2001/XMLSchema";
xmlns:f="http://fxsl.sf.net/";
exclude-result-prefixes="xs f"


<xsl:import href="func-map.xsl"/> <xsl:import href="func-flip.xsl"/>

<!--
      XSLT functions:
                    xsltSort()
-->

<xsl:function name="f:xsltSort" as="item()*">
  <xsl:param name="pSeq" as="item()*"/>
  <xsl:param name="pCriteria" as="node()*"/>

  <xsl:perform-sort select="$pSeq">
    <xsl:sort select=
         "string-join(
                      f:map(f:flip(f:map(), .), $pCriteria)
                      ,
                      ''
                      )
         "
    />
  </xsl:perform-sort>
</xsl:function>

</xsl:stylesheet>


The $pSeq argument contains the sequence of items to be sorted.


The $pCriteria argument is a sequence of functions (template
references), each of which produces a (xs:string) part of the sort
key, when this (sort-key-part-generating)function is applied to the
current item of the sequence $pSeq .

Then all such sort-key parts are string-join()-ed to produce the
complete sort key of the current item of the sequence $pSeq  being
sorted. Because their results are concatenated from left to right, a
function, which is specified to the left of another function in the
sequence $pCriteria has higher priority in determining the sort order
of any two items of $pSeq.


The function f:element() used in the test code is an accessor function.


f:element($pNode, $someStrName)

produces the sequence:

$pNode/*[name() = $someStrName]


All functions described can be downloaded from the latest FXSL CVS.



-- Cheers, Dimitre Novatchev --------------------------------------- Truly great madness cannot be achieved without significant intelligence. --------------------------------------- To invent, you need a good imagination and a pile of junk ------------------------------------- You've achieved success in your field when you don't know whether what you're doing is work or play



On 3/28/07, Angela Williams <Angela.Williams@xxxxxxxxxxxxxxxxxx> wrote:
Aha!

My esteemed colleague came up with a better idea - gosh, I hate it when
I forget the power of xpath!

<?xml version="1.0" encoding="UTF-8"?>
<employees>
 <employee hireDate="04/23/1999">
   <last>Hill</last>
   <first>Phil</first>
   <salary>100000</salary>
 </employee>

 <employee hireDate="09/01/1998">
   <last>Herbert</last>
   <first>Johnny</first>
   <salary>95000</salary>
 </employee>

 <employee hireDate="08/20/2000">
   <last>Hill</last>
   <first>Graham</first>
   <salary>89000</salary>
 </employee>

 <sort order="1">last</sort>
 <sort order="2">first</sort>
</employees>

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
version="2.0" xmlns:saxon="http://saxon.sf.net/";>

<xsl:output method="text" />

 <xsl:template match="employees">
   <xsl:variable name="sort1" select="sort[@order='1']" />
   <xsl:variable name="sort2" select="sort[@order='2']" />
   <xsl:variable name="sort3" select="sort[@order='3']" />
   <xsl:variable name="sort4" select="sort[@order='4']" />

   <xsl:for-each select="employee">
     <xsl:sort
         select="if ($sort1) then saxon:evaluate($sort1) else 'foo'" />
     <xsl:sort
         select="if ($sort2) then saxon:evaluate($sort2) else 'foo'" />
     <xsl:sort
         select="if ($sort3) then saxon:evaluate($sort3) else 'foo'" />
     <xsl:sort
         select="if ($sort4) then saxon:evaluate($sort4) else 'foo'" />


Last: <xsl:apply-templates select="last" /> First: <xsl:apply-templates select="first" /> Salary: <xsl:apply-templates select="salary" /> Hire Date: <xsl:apply-templates select="@hireDate" /> <xsl:text> </xsl:text> </xsl:for-each> </xsl:template> </xsl:stylesheet>

-----Original Message-----
From: Angela Williams
Sent: Tuesday, March 27, 2007 12:59 PM
To: 'xsl-list@xxxxxxxxxxxxxxxxxxxxxx'
Subject: RE: [xsl] Dynamically define number of xsl:sort stmts using
parameters

Thanks for both of your quick responses.  You've confirmed I am on the
right path.  There is a lot to think about.

Charles Knell wrote:
>use a stylesheet to create a stylesheet that does the transformation.

I think this would be possible, if complicated.  The user is not limited
on the number of tables they can insert, so there could be several
templates generated. It seems I would still end up with a variation of
3, as I would want to consolidate the number of templates to a minimum,
since the user could specify multiple tables with the same number of
sort statements. This would also mean I would have to output the master
stylesheet on the fly, too, to get the list of includes correct.

> (Do your users check off the columns they want to sort by in some user
>interface?

Yes.

Abel Braaksma wrote:
> I looked up an old template of myself where I faced a similar problem.

>The easy part is the number of sort statements. Just limit the amount
>to, say, 10, and create 10 sort statements.

This would certainly be the most expedient solution in the short term.

Again,
Thanks!

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