Dear All ...

I thought that I had solved my Grouping/Filtering problem with the following XSL (see below) ... but it wasn't as easy as I believed:

In my example, I use a filter on the 'match' clause of the 'key' statement to limit the data to two months (here February and March 2006): mnth>='200602' and mnth<='200603' (see XSL below).

This filter works OK and the key returns exactly the data that I need:
1. A count of the number of teams: count(key('kteam',team)/team)
2. Sum of total sales by team: sum(key('kteam',team)/sales)
... for the specific period Feb to Mar.

But I found that, when I tried to integrate this into my live version, the XML/XSL parser refused to process the 'key' statement with the variables I was trying to pass ($monthfrom and $monthuntil). Here in my test version the filtering works because I declare literal values (e.g. '200602') but in my live version I need to pass filter variables (i.e. any combination of months) and that doesn't work (on the key statement).

I hope that someone can take a quick look at my solution and suggest a method to apply variables to the filter? Indeed, I tried applying the filter to the 'for-each select=' clause (along with the generate-id() statement) but this returned incorrect data (i.e. didn't filter correctly). Maybe there is another location (for the filter) or an alternative syntax that I could use?

Many thanks for any tips that you can give me.

Regards,
Alan Searle

PS: And this XSL might also be an interesting example for any newbies out there who are trying to understand principles of grouping and filtering.

-------------------------------
XSL ... Filter on mnth, count and sum on team

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

<xsl:key name="kteam" match="xmlout[(mnth&gt;='200602' and mnth&lt;='200603')]" use="team"/>

  <xsl:template match="root">
    <table border="1">
      <tr><th colspan="4"> Team Overview <xsl:value-of select="team"/></th></tr>

      <tr><th>Team</th><th>Count</th><th>sales</th><th>id</th></tr>
      <xsl:for-each select="xmlout[(generate-id()=generate-id(key('kteam',team)[1]))]">
        <tr>
          <td><xsl:value-of select="team"/></td>
          <td><xsl:value-of select="count(key('kteam',team)/team)"/></td>
          <td><xsl:value-of select="sum(key('kteam',team)/sales)"/></td>
          <td><xsl:value-of select="generate-id(.)"/></td>
        </tr>
      </xsl:for-each>
    </table>
   <br />
  </xsl:template>

</xsl:stylesheet>
-----------------------------------
XML ... simplified version of the data

<?xml-stylesheet href="team.xsl" type="text/xsl"?>
<?xml version="1.0" encoding="UTF-8"?>
<root>
<xmlout><mnth>200601</mnth><team>A</team><sales>23</sales>
</xmlout><xmlout>
<mnth>200601</mnth><team>B</team><sales>33</sales>
</xmlout><xmlout>
<mnth>200601</mnth><team>C</team><sales>98</sales>
</xmlout><xmlout>
<mnth>200602</mnth><team>A</team><sales>14</sales>
</xmlout><xmlout>
<mnth>200602</mnth><team>B</team><sales>65</sales>
</xmlout><xmlout>
<mnth>200602</mnth><team>C</team><sales>76</sales>
</xmlout><xmlout>
<mnth>200603</mnth><team>A</team><sales>34</sales>
</xmlout><xmlout>
<mnth>200603</mnth><team>B</team><sales></sales>
</xmlout><xmlout>
<mnth>200603</mnth><team>C</team><sales>56</sales>
</xmlout>
</root>

Resetting keys ...

I was wondering that maybe what I need to solve this problem is the ability to reset or refilter a key?

For example my first version the following unfiltered key works:

<xsl:key name="kteam" match="xmlout" use="team"/>

Then in the filtered version this also works:

<xsl:key name="kteam" match="xmlout[(mnth&gt;='200602' and mnth&lt;='200603')]" use="team"/>

... i.e. a filter is applied to the dataset 'xmlout'.

But then, when I try to add parameters, it falls over:

<xsl:key name="kteam" match="xmlout[(mnth&gt;=$monthfrom and mnth&lt;=$monthuntil)]" use="team"/>

Here I was wondering if there is any way to redefine a key at any other point in the XSL? My plan would be to declare the data as 'xmlout' but then, just before display, redeclare the key with the required filter?

What do you think? Am I on the right track?

Regards,
Alan.

No, you can't use keys in this way. You have to define all the dynamic conditions at the time you use the key (e.g. by applying a predicate to the result: key('kteam', $team)[mnth >= x and mnth <= y].



Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

Hi Michael,

Fantastic: Your snippet of syntax got me moving and now the grouping/summing is displaying correctly with the filter.

Many thanks,
Alan Searle