Nested grouping based on a condition - xslt

Question

I am learning on xslt group-by. I have a sample xml as below
<?xml version="1.0" encoding="UTF-8"?>
<h1>
<a1>abcd</a1>
<a2>efgh</a2>
<h2>
<b1>IV-3</b1>
<b2>20.00</b2>
<h3>
<c1>VCH</c1>
<c2>1001</c2>
<c3>100.00</c3>
</h3>
</h2>
<h2>
<b1>IV-3</b1>
<b2>50.00</b2>
</h2>
<h2>
<b1>IV-3</b1>
<b2>10.00</b2>
<h3>
<c1>VCH</c1>
<c2>1001</c2>
<c3>300.00</c3>
</h3>
</h2>
<h2>
<b1>IV-3</b1>
<b2>30.00</b2>
</h2>
</h1>
I need to group-by with the b1 value first and sum up b2 values and if h3 node is present , need to group-by c2 and sum up c3 values of that group. My xslt is as below.
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:fn="http://www.w3.org/2005/xpath-functions">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
<xsl:template match="h1">
<t1>
<d1>
<xsl:value-of select="a1"/>
</d1>
<d2>
<xsl:value-of select="a2"/>
</d2>
<xsl:for-each-group select="h2" group-by="b1">
<xsl:if test="current-group()/count(h3) > 0 ">
<xsl:for-each-group select="current-group()/h3" group-by="c2">
<t2>
<e1>
<xsl:value-of select="../b1"/>
</e1>
<e2>
<xsl:value-of select="format-number(sum(current-group()/../b2),'#.00')"/>
</e2>
<e3>
<xsl:value-of select="format-number(sum(current-group()/c3),'#.00')"/>
</e3>
</t2>
</xsl:for-each-group>
</xsl:if>
<xsl:if test="current-group()/count(h3) = 0 ">
<t2>
<e1>
<xsl:value-of select="b1"/>
</e1>
<e2>
<xsl:value-of select="format-number(sum(current-group()/b2),'#.00')"/>
</e2>
<e3>
<xsl:value-of select="11111"/>
</e3>
</t2>
</xsl:if>
</xsl:for-each-group>
</t1>
</xsl:template>
</xsl:stylesheet>
The aggrigate value I am getting for e2 is not correct, if h3 is not present. The expected result is
<?xml version="1.0" encoding="UTF-8"?>
<t1 xmlns:fn="http://www.w3.org/2005/xpath-functions" xmlns:xs="http://www.w3.org/2001/XMLSchema">
<d1>abcd</d1>
<d2>efgh</d2>
<t2>
<e1>IV-3</e1>
<e2>30.00</e2>
<e3>400.00</e3>
</t2>
<t2>
<e1>IV-3</e1>
<e2>80.00</e2>
<e3>11111</e3>
</t2>
</t1>
Thanks for the help!

Answer 1

You want to group on two values at once, so you must change your group-by selector.
From
<xsl:for-each-group select="h2" group-by="b1">
To
<xsl:for-each-group select="h2" group-by="concat(b1, '|', boolean(h3))">
Apart from that your code works.
<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:fn="http://www.w3.org/2005/xpath-functions">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes" />
<xsl:template match="h1">
<t1>
<d1>
<xsl:value-of select="a1" />
</d1>
<d2>
<xsl:value-of select="a2" />
</d2>
<xsl:for-each-group select="h2" group-by="concat(b1, '|', boolean(h3))">
<xsl:if test="current-group()/h3">
<xsl:for-each-group select="current-group()/h3" group-by="c2">
<t2>
<e1>
<xsl:value-of select="../b1" />
</e1>
<e2>
<xsl:value-of select="format-number(sum(current-group()/../b2), '#.00')" />
</e2>
<e3>
<xsl:value-of select="format-number(sum(current-group()/c3), '#.00')" />
</e3>
</t2>
</xsl:for-each-group>
</xsl:if>
<xsl:if test="not(current-group()/h3)">
<t2>
<e1>
<xsl:value-of select="b1" />
</e1>
<e2>
<xsl:value-of select="format-number(sum(current-group()/b2), '#.00')" />
</e2>
<e3>
<xsl:value-of select="11111" />
</e3>
</t2>
</xsl:if>
</xsl:for-each-group>
</t1>
</xsl:template>
</xsl:stylesheet>
This stylesheet produces the wanted output
<t1 xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:fn="http://www.w3.org/2005/xpath-functions">
<d1>abcd</d1>
<d2>efgh</d2>
<t2>
<e1>IV-3</e1>
<e2>30.00</e2>
<e3>400.00</e3>
</t2>
<t2>
<e1>IV-3</e1>
<e2>80.00</e2>
<e3>11111</e3>
</t2>
</t1>
Notes
boolean(h3) emits the strings 'true' or 'false' depending on the existence of <h3> elements
in the same manner, your <xsl:if> tests can be simplified to current-group()/h3 and not(current-group()/h3), respectively (the empty node set evaluates to false)
you should declare exclude-result-prefixes="xs fn" to remove the unnecessary namespace declarations from the output document.