Group/merge childs of same nodes in xml/xslt when repeating upper nodes

Question

As an addition to my orginal post Group/merge childs of same nodes in xml/xslt I ran into the problem of having that structure repeated multiple times for different nodes (wihtin nodes higher in the hierarchy) e.g.,

<Collection>
    <Questionnaire Name="Preferences" VersionID="3QW">
        <Subject ID="2355">
            <EventData Name="First Part">
                <FormData Name="Past">
                    <GroupData ID="xxx" Key="4" Temp="yyy">
                        <ItemData ID="zzz" Value="3"/>
                    </GroupData>
                    <GroupData ID="xxx" Key="4" Temp="yyy">
                        <ItemData ID="qqq" Value="4"/>
                    </GroupData>
                    ...
                </FormData>
                <FormData Name="Present">
                    <GroupData ID="yyy" Key="9" Temp="yyy">
                        <ItemData ID="www" Value="32"/>
                    </GroupData>
                    ...
                </FormData>             
            </EventData>
            <EventData Name="SecondPart">
                ...
            </EventData>
        </Subject>
        <Subject ID="9812">
            ...
        </Subject>
    </Questionnaire>    
</Collection>

After trying variations on the suggestions I reveived and some other things I am stuck. I think it has something to do with multiple levels (and GroupData being spread over upper/grandparent nodes in which it will be a child) and then it possiblly does not have unique IDs anymore. So how can I get the childs of each GroupData node into one GroupData node (matched on ID and sometimes Key, since the latter is not always present)? Note: The same GroupData nodes (with corresponding attributes) must be merged into one GroupData node in each FormData node.

@SeanB.Durkin - the question is, "So how can I get the childs of each GroupData node into one GroupData node (matched on ID and sometimes Key, since the latter is not always present)?" — ABach, Aug 15 '12 at 14:26
Mat90, People need to understand what is the wanted result and what are the rules for the transformation. Please, edit the question and provide this missing information. Also, please, never have elipsis in the provided XML document -- this can be very confusing. — Dimitre Novatchev, Aug 15 '12 at 14:29
Even looking at your previous question, it took me a while to understand what you want. You want GroupData nodes merged by the product of ID, Key and FormData. That is to say GroupData merged by ID and Key, **per** FormData element. — Sean B. Durkin, Aug 15 '12 at 15:03

Sean B. Durkin · Answer 1 · 2012-08-15T15:29:50.440

Here are two XSLT 1.0 solutions.

One solution is to take Dimite's solution from your first question, and just expand the key to include FormData...

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>
 <xsl:strip-space elements="*"/>

 <xsl:key name="kGDByIdKey" match="FormData/GroupData"
  use="concat(@ID, '+', @Key, '+', generate-id(..))"/>

 <xsl:template match="@*|node()">
     <xsl:copy>
       <xsl:apply-templates select="@*|node()"/>
     </xsl:copy>
 </xsl:template>

 <xsl:template match=
 "FormData/GroupData
    [generate-id()
    =
     generate-id(key('kGDByIdKey', concat(@ID, '+', @Key, '+', generate-id(..)))[1])
     ]">
    <xsl:copy>
      <xsl:apply-templates select=
       "@*|key('kGDByIdKey', concat(@ID, '+', @Key, '+', generate-id(..)))/node()"/>
    </xsl:copy>
 </xsl:template>

  <xsl:template match="GroupData"/>
</xsl:stylesheet>

Another solution moves the grouping test from the template match condition to the the invoking xsl:apply-templates in the parent FormData ...

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>
 <xsl:strip-space elements="*"/>

 <xsl:key name="kGDByIdKey" match="FormData/GroupData" use="concat(@ID, '+', @Key)" />

 <xsl:template match="@*|node()">
     <xsl:copy>
       <xsl:apply-templates select="@*|node()"/>
     </xsl:copy>
 </xsl:template>

 <xsl:template match="FormData">
     <xsl:copy>
       <xsl:apply-templates select="
          @* |
          node()[not(self::GroupData)] |
          GroupData[generate-id() =
                    generate-id(key('kGDByIdKey', concat(@ID, '+', @Key))[1])]"/>
     </xsl:copy>
 </xsl:template>

 <xsl:template match="FormData/GroupData">
     <xsl:copy>
       <xsl:apply-templates select="@*|
           key('kGDByIdKey', concat(@ID, '+', @Key))/node()"/>
     </xsl:copy>
 </xsl:template>
  <xsl:template match="GroupData"/>
</xsl:stylesheet>

Both stylesheets assume that GroupData's parent is only ever FormData. Any GroupData which does not have a FormData parent is removed.

Group/merge childs of same nodes in xml/xslt when repeating upper nodes

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