XSLT grouping child nodes for each sibling - xslt

Question

I have been working with XSLT lately, but now I got to a new problem trying to group a new xml file. I can't work out how to put a scope on the grouping. I want to group the <Detail> inside every <Info> node. Simple sample file:
<?xml version="1.0" encoding="utf-8"?>
<File>
<Info>
<Id>1111</Id>
<Detail type="A" group="1" >
<Data>
<Nr>1</Nr>
</Data>
<Data>
<Nr>2</Nr>
</Data>
</Detail>
<Detail type="B" group="1">
<Data>
<Nr>3</Nr>
</Data>
<Data>
<Nr>4</Nr>
</Data>
</Detail>
<Detail type="B" group="2">
<Data>
<Nr>5</Nr>
</Data>
</Detail>
<Detail type="A" group="1">
<Data>
<Nr>6</Nr>
</Data>
</Detail>
</Info>
<Info>
<Id>2222</Id>
<Detail type="A" group="1" >
<Data>
<Nr>1</Nr>
</Data>
</Detail>
<Detail type="B" group="1">
<Data>
<Nr>2</Nr>
</Data>
</Detail>
<Detail type="A" group="1">
<Data>
<Nr>3</Nr>
</Data>
</Detail>
</Info>
</File>
The output should be
<?xml version="1.0" encoding="utf-8"?>
<File>
<Info>
<Id>1111</Id>
<Detail type="A" group="1" >
<Data>
<Nr>1</Nr>
</Data>
<Data>
<Nr>2</Nr>
</Data>
<Data>
<Nr>6</Nr>
</Data>
</Detail>
<Detail type="B" group="1">
<Data>
<Nr>3</Nr>
</Data>
<Data>
<Nr>4</Nr>
</Data>
</Detail>
<Detail type="B" group="2">
<Data>
<Nr>5</Nr>
</Data>
</Detail>
</Info>
<Info>
<Id>2222</Id>
<Detail type="A" group="1" >
<Data>
<Nr>1</Nr>
</Data>
<Data>
<Nr>3</Nr>
</Data>
</Detail>
<Detail type="B" group="1">
<Data>
<Nr>2</Nr>
</Data>
</Detail>
</Info>
</File>
In my try I don't know how to copy the values from the <Info> element (ID, it could be other elements too), I just write out <Info> element, and every <Detail> gets grouped in the first <Info> element, leaving the last <Info> element empty.
Here is my xslt so far
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:key name="details" match="Detail"
use="concat(#type,'_',#group)"/>
<xsl:template match='/'>
<File>
<xsl:for-each select="File/Info">
<Info>
<xsl:for-each select="Detail[count(. | key('details', concat(#type,'_',#group))[1]) = 1]">
<xsl:sort select="concat(#type,'_',#group)" />
<Detail type="{#type}" group="{#group}">
<xsl:for-each select="key('details', concat(#type,'_',#group))">
<xsl:copy-of select="Data"/>
</xsl:for-each>
</Detail>
</xsl:for-each>
</Info>
</xsl:for-each>
</File>
</xsl:template>
</xsl:stylesheet>
and here is my result so far
<File>
<Info>
<Detail type="A" group="1">
<Data>
<Nr>1</Nr>
</Data>
<Data>
<Nr>2</Nr>
</Data>
<Data>
<Nr>6</Nr>
</Data>
<Data>
<Nr>1</Nr>
</Data>
<Data>
<Nr>3</Nr>
</Data>
</Detail>
<Detail type="B" group="1">
<Data>
<Nr>3</Nr>
</Data>
<Data>
<Nr>4</Nr>
</Data>
<Data>
<Nr>2</Nr>
</Data>
</Detail>
<Detail type="B" group="2">
<Data>
<Nr>5</Nr>
</Data>
</Detail>
</Info>
<Info />
</File>
Thanks for any help :)

Answer 1

This transformation:
<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="kDetailChildren" match="Detail"
use="concat(generate-id(..),'+',#type,'+',#group)"/>
<xsl:template match="node()|#*">
<xsl:copy>
<xsl:apply-templates select="node()|#*"/>
</xsl:copy>
</xsl:template>
<xsl:template match=
"Detail
[not(generate-id()
=
generate-id(key('kDetailChildren',
concat(generate-id(..),'+',#type,'+',#group)
)[1])
)]"/>
<xsl:template match="Detail">
<Detail>
<xsl:apply-templates select="#*"/>
<xsl:apply-templates select=
"key('kDetailChildren',
concat(generate-id(..),'+',#type,'+',#group)
)/node()"/>
</Detail>
</xsl:template>
</xsl:stylesheet>
When applied on the provided XML document:
<File>
<Info>
<Id>1111</Id>
<Detail type="A" group="1" >
<Data>
<Nr>1</Nr>
</Data>
<Data>
<Nr>2</Nr>
</Data>
</Detail>
<Detail type="B" group="1">
<Data>
<Nr>3</Nr>
</Data>
<Data>
<Nr>4</Nr>
</Data>
</Detail>
<Detail type="B" group="2">
<Data>
<Nr>5</Nr>
</Data>
</Detail>
<Detail type="A" group="1">
<Data>
<Nr>6</Nr>
</Data>
</Detail>
</Info>
<Info>
<Id>2222</Id>
<Detail type="A" group="1" >
<Data>
<Nr>1</Nr>
</Data>
</Detail>
<Detail type="B" group="1">
<Data>
<Nr>2</Nr>
</Data>
</Detail>
<Detail type="A" group="1">
<Data>
<Nr>3</Nr>
</Data>
</Detail>
</Info>
</File>
produces the wanted, correct result:
<File>
<Info>
<Id>1111</Id>
<Detail type="A" group="1">
<Data>
<Nr>1</Nr>
</Data>
<Data>
<Nr>2</Nr>
</Data>
<Data>
<Nr>6</Nr>
</Data>
</Detail>
<Detail type="B" group="1">
<Data>
<Nr>3</Nr>
</Data>
<Data>
<Nr>4</Nr>
</Data>
</Detail>
<Detail type="B" group="2">
<Data>
<Nr>5</Nr>
</Data>
</Detail>
</Info>
<Info>
<Id>2222</Id>
<Detail type="A" group="1">
<Data>
<Nr>1</Nr>
</Data>
<Data>
<Nr>3</Nr>
</Data>
</Detail>
<Detail type="B" group="1">
<Data>
<Nr>2</Nr>
</Data>
</Detail>
</Info>
</File>
Explanation:
Proper use of the identity rule and the Muenchian grouping method using composite keys.
Note how the parent's identity is included in the key.