Re: [xsl] Grouping and then more grouping

["G. Ken Holman" <gkholman@xxxxxxxxxxxxxxxxxxxx>]

At 2011-08-15 21:45 +0000, Alex Muir wrote:
> I'm trying to group the identical groups by id together such that given
> ...

First of all, you are violating the principle of xml:id= by having 
more than one element with the same value for xml:id=.  xml:id= 
attributes should be unique across an XML document.  But that won't 
prevent it from being used.

> I'll get a result that merges the like groups together and copies items
> ...

I'm not sure why you have "Sea" before "Air" when "Air" comes before 
"Sea" in your input data.

> I've written the following which groups the first level and played
> around with getting something that moves to lower group levels as I
> need however I'm not sure what to do to descend through each group
> joining them together by id.

This was interesting because I would say it isn't a typical use of 
grouping.  It can be done and I have an answer below that I hope helps.

Typical sub-grouping is grouping under the same ancestor, yet this is 
grouping items found under different ancestors.  So, whenever I 
created a population for grouping, I went to all of the child groups 
of the current group, but I only acted on the first of each current 
group.  The solution fell together very quickly and is quite compact.

I just can't figure out how you expect "Sea" to come before "Air" 
when "Air" comes before "Sea" in your input.  Are you not mentioning 
an ordering requirement?

. . . . . . . . . . . Ken


t:\ftemp>type alex.xml
<?xml version="1.0" encoding="UTF-8"?>
<root>
  <group xml:id="MILHIS_Yes">
    <name>Yes</name>
    <group xml:id="MILHIS_Vehicles">
      <name>Vehicles</name>
      <group xml:id="MILHIS_Air">
        <name>Air</name>
        <group xml:id="MILHIS_Aeroplane">
          <name>Aeroplane</name>
          <item xml:id="MILHIS_Attack_Aircraft">
            <name>Attack Aircraft</name>
          </item>
        </group>
      </group>
    </group>
  </group>
  <group xml:id="MILHIS_Yes">
    <name>Yes</name>
    <group xml:id="MILHIS_Vehicles">
      <name>Vehicles</name>
      <group xml:id="MILHIS_Air">
        <name>Air</name>
        <group xml:id="MILHIS_Aeroplane">
          <name>Aeroplane</name>
          <item xml:id="MILHIS_Bomber_Aircraft">
            <name>Bomber Aircraft</name>
          </item>
        </group>
      </group>
    </group>
  </group>
  <group xml:id="MILHIS_Yes">
    <name>Yes</name>
    <group xml:id="MILHIS_Vehicles">
      <name>Vehicles</name>
      <group xml:id="MILHIS_Sea">
        <name>Sea</name>
        <group xml:id="MILHIS_Ship">
          <name>Ship</name>
          <item xml:id="MILHIS_Aircraft_Carrier">
            <name>Aircraft Carrier</name>
          </item>
        </group>
      </group>
    </group>
  </group>
</root>
t:\ftemp>call xslt2 alex.xml alex.xsl
<?xml version="1.0" encoding="UTF-8"?>
<group xml:id="MILHIS_Yes">
   <name>Yes</name>
   <group xml:id="MILHIS_Vehicles">
      <name>Vehicles</name>
      <group xml:id="MILHIS_Air">
         <name>Air</name>
         <group xml:id="MILHIS_Aeroplane">
            <name>Aeroplane</name>
            <item xml:id="MILHIS_Attack_Aircraft">
               <name>Attack Aircraft</name>
            </item>
            <item xml:id="MILHIS_Bomber_Aircraft">
               <name>Bomber Aircraft</name>
            </item>
         </group>
      </group>
      <group xml:id="MILHIS_Sea">
         <name>Sea</name>
         <group xml:id="MILHIS_Ship">
            <name>Ship</name>
            <item xml:id="MILHIS_Aircraft_Carrier">
               <name>Aircraft Carrier</name>
            </item>
         </group>
      </group>
   </group>
</group>
t:\ftemp>type alex.xsl
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
  version="2.0">

<xsl:output indent="yes"/>
<xsl:template match="root">
  <xsl:call-template name="CopyGroup">
    <xsl:with-param name="groups" select="group"/>
  </xsl:call-template>
</xsl:template>
<xsl:template name="CopyGroup">
  <xsl:param name="groups"/>
  <xsl:for-each-group select="$groups" group-by="@xml:id">
      <group>
        <!--copy the common information about this group-->
        <xsl:copy-of select="@xml:id, name, $groups/item"/>
        <!--process subgroups based on all children of group members-->
        <xsl:call-template name="CopyGroup">
          <xsl:with-param name="groups" select="current-group()/group"/>
        </xsl:call-template>
      </group>
  </xsl:for-each-group>
</xsl:template>
</xsl:stylesheet>
t:\ftemp>rem Done!


--
Contact us for world-wide XML consulting & instructor-led training
Crane Softwrights Ltd.          http://www.CraneSoftwrights.com/s/
G. Ken Holman                 mailto:gkholman@xxxxxxxxxxxxxxxxxxxx
Legal business disclaimers:  http://www.CraneSoftwrights.com/legal