[xsl] Grouping

["Chris D'Iorio" <cdiorio at sympatico dot ca>]

I've been banging my head against a brick wall for a few days now. Having 
seen the level of expertise here, and given my own preliminary stumblings 
in xml and xslt, I feel a little foolish trying to poach some assistance 
when I really ought to be studying more, but I don't seem to be able to 
find any answers. I'd be very grateful for any assistance with the 
following problem:

I have the following XML:

<newsbriefs>
         <item>
                 <date>2001-02-08</date>
                 <title>Newsletter No. 14</title>
                 <category type="news"/>
                 <jurisdiction name="All"/>
                 <summary>The Regie des Rentes has released an English 
version of La Lettre No. 14, which discusses the changes brought about by 
Bill 102.</summary>
                 <source>
                         <link 
href="http://www.rrq.gouv.qc.ca/an/prive/lettrercr/lettre14.htm">Newsletter</link>
                 </source>
                 <news/>
                 <backgrounders/>
                 <progress>
                         <first_reading/>
                         <second_reading/>
                         <third_reading/>
                         <royal_assent/>
                         <in_force/>
                 </progress>
                 <subjects>
                         <subject_ref reference="pensions"/>
                         <subject_ref reference="governance"/>
                 </subjects>
         </item>
         <item>
                 <date>2001-02-09</date>
                 <title>Labour Force statistics</title>
                 <category type="news"/>
                 <jurisdiction name="All"/>
                 <summary>Employment was virtually unchanged in January. 
The unemployment rate edged up 0.1 percentage points to 6.9%.</summary>
                 <source>
                         <link 
href="http://www.statcan.ca/Daily/English/010209/d010209a.htm">StatsCan 
Daily</link>
                 </source>
                 <news/>
                 <backgrounders/>
                 <progress>
                         <first_reading/>
                         <second_reading/>
                         <third_reading/>
                         <royal_assent/>
                         <in_force/>
                 </progress>
                 <subjects>
                         <subject_ref reference="general"/>
                 </subjects>
         </item>

Many of the <item>s in my file have multiple <subject_ref> tags. I'm trying 
(with no success) to find a way to group them by subject_ref/@reference, 
but with no luck. I've gone through the archives, and found reference to a 
solution by Steve Muench involving the use of keys. I've (very 
unsuccessfully) tried to make the following work:

         <xsl:key name="group" match="subject_ref" use="@reference"/>

         [...]

         <xsl:for-each 
select="//subject_ref[generate-id(.)=generate-id(key('group', 
@reference)[1])]">

         [...]

Do I have a problem because of the fact that I have more than one 
<subject_ref > child for many of the <subjects> nodes in my xml?

I would really appreciate any pointers on how to make this work.

Chris D'Iorio
inRatio Inc.


 XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list