for-each-group and differing attributes values

Kenneth.Dougherty · March 10th, 2011, 03:25 PM

Hello,

I was hoping someone might be able to provide some advice for the following problem.

Xsl:for-each-group is being used to create a list of items with unique values. The difficulty is the attributes of any element will not be processed unless it belongs to the first instance.

For example

The XML

Code:

<group>
 <supplyli>
    <supply change=âaddâ>item x </supply>
    <supply>item y </supply>
    <supply>item z </supply>
    <supply>item x </supply>
    <supply change=âaddâ>item y </supply>
    <supply>item z </supply>
  </supplyli>
</group>

is being processed by the xslt

Code:

<xsl:for-each-group select="descendant::supplyli/supply" group-by=".">
  <fo:block>
    <xsl:if test="@change='modify' or @change='add'">
      <xsl:call-template name="rev.bar"/>
    </xsl:if>
    <xsl:apply-templates/>
  </fo:block>
</xsl:for-each-group>

The result is that item x, item y, and item z are each processed, and appear only once. In addition, rev.bar gets called for item x as the first instance contains the change attribute, but rev.bar does not get called for item y as its first instance does not.

The appearance in the output pdf would be

item x |
item y
item z

[ | being the output from rev.bar]

The desired outcome would be to process the two xâs and yâs differently because of their differing attributes, leading to the following output

item x |
item y
item x
item y |
item z

Thank you for reviewing the issue. Any suggestions would be appreciated.

samjudson · March 10th, 2011, 03:50 PM

You just need to change the group-by attribute to be something that you actually want to group by, e.g. group-by="concat(.,@change)"

Sam

mhkay · March 11th, 2011, 04:51 AM

First, as Sam says, if you want elements with differing attributes to go in different groups then you need to put them in different groups, by choosing a grouping key that distinguishes them. How to do that depends on a better knowledge of your data than you've given us.

Alternatively, you might want to keep the grouping as it is, but then when processing each group look at what you find in it (using current-group()) rather than only looking at the first element in the group. For example, you could do a second level of grouping based on the change attribute:

Code:

<xsl:for-each-group select="descendant::supplyli/supply" group-by=".">
  <fo:block>
    <xsl:for-each-group select="current-group()" select="(@change, '')[1]">
       ...
    </xsl:for-each-group>
  </fo:block>
</xsl:for-each-group>

The inner grouping key here will create one group for change="add", one for change="delete", etc, and one for elements with no @change attribute.

Kenneth.Dougherty · March 11th, 2011, 01:30 PM

Thank you for the help, Sam and Michael. Sam's solution worked for this issue, and Michael's suggestions helped with a similar problem.