XSLT sorted node processing - xslt

Question

Context node:
<a>
<c refid="1" />
<c refid="2" />
<c refid="3" />
<c refid="4" />
<c refid="5" />
</a>
It gets the nodes referred to above, using a proprietary command:
<xsl:for-each select="get-a(#refid)">
<a id="1">
<f att1="C"/>
<f att2="I"/>
</a>
<a id="2">
<f att1="C"/>
<f att2="I"/>
</a>
<a id="3">
<!--doesn't have f att1-->
<f att2="I"/>
</a>
<a id="4">
<f att1="R"/>
<f att2="S"/>
</a>
<a id="5">
<f att1="G"/>
<f att2="I"/>
</a>
At present, I have it call a template within a for-each, but that will only do each node separately, obviously.
But it must process them first based on the att2 value (these are set values, always I or S, so no problem), and then within that, based on att1 value to produce something like below, the first P node being the problem:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="2.0">
<!--xsl:output method="xml" indent="no" encoding="UTF-8"/-->
<!-- This takes the first asset (betting that it's correct...) and uses it to establish the parameters below -->
<xsl:variable name="rootSourceAssetXml">
<xsl:copy-of select="/asset[1]"/>
<!--xsl:copy-of select="./asset"/-->
</xsl:variable>
<xsl:template match="/">
<xsl:variable name="xml">
<O>
<xsl:for-each select="$rootSourceAssetXml/asset/child_asset_rel[#key='user.']">
<xsl:sort select="cs:get-asset(#child_asset)/f/#att2" order="ascending" data-type="text"/>
<xsl:sort select="cs:get-asset(#child_asset)/f/#att1" order="descending" data-type="text"/>
<xsl:variable name="getChapter">
<xsl:variable name="getChapterXML" select="cs:get-asset(#child_asset)"/>
<xsl:for-each select="$getChapterXML">
<xsl:if test="$getChapterXML/f/#att2='ebook'">
<xsl:copy-of select="$getChapterXML"/>
</xsl:if>
</xsl:for-each>
</xsl:variable>
<xsl:call-template name="Group">
<xsl:with-param name="thingGroup" select="$getChapter"/>
<xsl:with-param name="resourceTypeWeb" select="'EBook'"/>
</xsl:call-template>
<xsl:variable name="getChapter">
<xsl:variable name="getChapterXML" select="cs:get-asset(#child_asset)"/>
<xsl:for-each select="$getChapterXML">
<xsl:if test="$getChapterXML/f att2='instructor'">
<xsl:copy-of select="$getChapterXML"/>
</xsl:if>
</xsl:for-each>
</xsl:variable>
<xsl:call-template name="Group">
<xsl:with-param name="thingGroup" select="$getChapter"/>
<xsl:with-param name="resourceTypeWeb" select="'Instructor'"/>
</xsl:call-template>
</xsl:for-each>
</O>
</xsl:variable> <!-- Closes xml variable block -->
</xsl:template>
<xsl:template name="Group">
<xsl:param name="thingGroup"/>
<xsl:param name="resourceTypeWeb"/>
<xsl:variable name="eachAsset">
<xsl:for-each select="$thingGroup">
<xsl:copy-of select="$thingGroup/asset"/>
</xsl:for-each>
</xsl:variable>
<xsl:variable name="productResourceDescriptionGroupWeb" select="$eachAsset/asset/asset_feature[#feature='XXX:product-resource-description-group-web']/#value_string"/>
<xsl:variable name="productResourceDescriptionDetailWeb" select="$eachAsset/asset/asset_feature[#feature='XXX:product-resource-description-detail-web']/#value_string"/>
<xsl:for-each select="$eachAsset/asset">
<P>
<xsl:attribute name="e"><xsl:value-of select="$resourceTypeWeb"/></xsl:attribute>
<xsl:attribute name="d"><xsl:value-of select="$productResourceDescriptionGroupWeb"/></xsl:attribute>
<xsl:call-template name="Detail">
<xsl:with-param name="resourceTypeWeb" select="$resourceTypeWeb"/>
<xsl:with-param name="topAssetTypeName" select="$topAssetTypeName"/>
<xsl:with-param name="thing" select="$eachAsset"/>
<xsl:with-param name="productResourceDescriptionDetailWeb" select="$productResourceDescriptionDetailWeb"/>
</xsl:call-template>
</P>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
Should produce this:
<O>
<P d="C" e="I"> <!-- This C is not a set value but a string, and it could be anything. Once the nodes with the same attribute are isolated, it is fine to grab the att value from node in position 1-->
<id1>
<!-- other info via call template; this works -->
</id1>
<id2>
<!-- other info via call template; this works -->
</id2>
</P>
<P d="NULL" e="I">
<id3>
<!-- other info via call template; this works -->
</id3>
</P>
<P d="G" e="I">
<id5>
<!-- other info via call template; this works -->
</id5>
</P>
<P d="R" e="S">
<id4>
<!-- other info via call template; this works -->
</id4>
</P>
</O>
I have tried for-each-group calling a different template, and for-each with a sort for the value of att1, and other methods with no success.
This gives the right order, but I cannot bring nodes with same C value together:
<xsl:sort select="a/f/#att2"/>
<xsl:sort select="a/f/#att1"/>
The logic should be
for each <a> with same att2 value
for each <a> with same att1 value
output a single P with d=att1 value
then process nodes with same att1
I know XSLT can't "loop" the way I'm used to with Perl, but I feel there is some way to do this by grouping or sorting, I just can't find the right combination. I keep getting so close, but then can't complete it.
Many thanks in advance.

Answer 1

Your question is (still) very confusing. Consider the following simplified example:
Input XML
<root>
<a id="1">
<f att1="C"/>
<f att2="I"/>
</a>
<a id="2">
<f att1="C"/>
<f att2="I"/>
</a>
<a id="3">
<!--doesn't have f att1-->
<f att2="I"/>
</a>
<a id="4">
<f att1="R"/>
<f att2="S"/>
</a>
<a id="5">
<f att1="G"/>
<f att2="I"/>
</a>
</root>
XSLT 2.0
<xsl:stylesheet version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
<xsl:template match="root">
<root>
<xsl:for-each-group select="a" group-by="f/#att2">
<xsl:for-each-group select="current-group()" group-by="if (f/#att1) then f/#att1 else 'NULL'">
<P d="{current-grouping-key()}" e="{f/#att2}">
<xsl:for-each select="current-group()">
<abc id="{#id}"/>
</xsl:for-each>
</P>
</xsl:for-each-group>
</xsl:for-each-group>
</root>
</xsl:template>
</xsl:stylesheet>
Result
<?xml version="1.0" encoding="UTF-8"?>
<root>
<P d="C" e="I">
<abc id="1"/>
<abc id="2"/>
</P>
<P d="NULL" e="I">
<abc id="3"/>
</P>
<P d="G" e="I">
<abc id="5"/>
</P>
<P d="R" e="S">
<abc id="4"/>
</P>
</root>
This shows how to implement your stated logic:
for each <a> with same att2 value
for each <a> with same att1 value
output a single P with d=att1 value
then process nodes with same att1
and nothing else.