RE: [xsl] xslt 2 grouping - solution and result: xsl-fo property list.

["Michael Kay" <michael dot h dot kay at ntlworld dot com>]

> Just to test my understanding please.
> 
>  <p>
>  <el att='a'>x</el>
>  <el att='b'>x</el>
>  <el att='c'>x</el>
>  <el att='d'>y</el>
>  </p>
> 
> 
> <xsl:template match='p'>
> <xsl:for-each-group select="e1" group-by=".">
>   <e1 name="{.}">
>     <xsl:for-each-group select="current-group()" group-by="@att">
>       <xsl:value-of select="concat(@att, ' ')"/>
>     </xsl:for-each>
>   </e1>
> </xsl:for-each>
> </xsl:template>
> 
> The outer grouping groups on element content, 
>    outputs the name of the outer group.

Within <xsl:for-each-group> there is a context node, this node is the
first e1 element in the current group. So name="{.}" outputs the string
value of this first e1 element: "x" for the first group, "y" for the
second. Since you were grouping by ".", this is actually the value that
all members of the group have in common, so any element in the group
would have been OK, but "." actually selects the first one.

>  The inner grouping takes each of these 'sequences' (is that the right
> word?)
>  and groups them by attribute value.
>  then outputs each these values.

That's right. The first time round the outer loop, current-group()
selects the three "x" element, the second time round, it selects the "y"
element.

The inner xsl:for-each-group could equally have been written:

<xsl:for-each select="distinct-values(current-group()/@att)"> since you
only want to select the distinct values of the attribute, not the group
of nodes associated with each distinct value.

Michael Kay
Software AG
home: Michael.H.Kay@ntlworld.com
work: Michael.Kay@softwareag.com 


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