XSLT transform to multiple complex types within for loop - xslt

Question

I have a requirment to transform a XML with the below structure
<CustomerStatements>
<CustomerStatement>
<Name>ABC</Name>
<ID>1</ID>
<Amt>10</Amt>
</CustomerStatement>
<CustomerStatement>
<Name>ABC</Name>
<ID>1</ID>
<Amt>20</Amt>
</CustomerStatement>
<CustomerStatement>
<Name>XYZ</Name>
<ID>2</ID>
<Amt>30</Amt>
</CustomerStatement>
<CustomerStatement>
<Name>XYZ</Name>
<ID>2</ID>
<Amt>40</Amt>
</CustomerStatement>
</CustomerStatements>
To
<Customers>
<Customer>
<Name>ABC</Name>
<Id>1</Id>
<Amounts>
<Amount>10</Amount>
<Amount>20</Amount>
</Amounts>
</Customer>
<Customer>
<Name>XYZ</Name>
<Id>2</Id>
<Amount>30</Amount>
<Amount>40</Amount>
</Customer>
</Customers>
I tried using a for loop and taking the name into a variable to compare the name in the next record, but this doesn't work. Can you any one help me with a sample XSLT psudo code.
Thanks

Answer 1

I. When this XSLT 1.0 solution:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:output omit-xml-declaration="no" indent="yes"/>
<xsl:strip-space elements="*"/>
<xsl:key
name="kCustByNameId"
match="CustomerStatement"
use="concat(Name, '+', ID)" />
<xsl:template match="/*">
<Customers>
<xsl:apply-templates
select="CustomerStatement[
generate-id() =
generate-id(key('kCustByNameId', concat(Name, '+', ID))[1])]" />
</Customers>
</xsl:template>
<xsl:template match="CustomerStatement">
<Customer>
<xsl:copy-of select="Name|ID" />
<Amounts>
<xsl:for-each select="key('kCustByNameId', concat(Name, '+', ID))/Amt">
<Amount>
<xsl:apply-templates />
</Amount>
</xsl:for-each>
</Amounts>
</Customer>
</xsl:template>
</xsl:stylesheet>
...is applied to the OP's original XML:
<CustomerStatements>
<CustomerStatement>
<Name>ABC</Name>
<ID>1</ID>
<Amt>10</Amt>
</CustomerStatement>
<CustomerStatement>
<Name>ABC</Name>
<ID>1</ID>
<Amt>20</Amt>
</CustomerStatement>
<CustomerStatement>
<Name>XYZ</Name>
<ID>2</ID>
<Amt>30</Amt>
</CustomerStatement>
<CustomerStatement>
<Name>XYZ</Name>
<ID>2</ID>
<Amt>40</Amt>
</CustomerStatement>
</CustomerStatements>
...the wanted result is produced:
<?xml version="1.0" encoding="UTF-8"?><Customers>
<Customer>
<Name>ABC</Name>
<ID>1</ID>
<Amounts>
<Amount>10</Amount>
<Amount>20</Amount>
</Amounts>
</Customer>
<Customer>
<Name>XYZ</Name>
<ID>2</ID>
<Amounts>
<Amount>30</Amount>
<Amount>40</Amount>
</Amounts>
</Customer>
</Customers>
The primary thing to look at here is Muenchian Grouping, which is the generally accepted method for grouping problems in XSLT 1.0.
II. Here's a more compact XSLT 2.0 solution:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0">
<xsl:output omit-xml-declaration="no" indent="yes"/>
<xsl:strip-space elements="*"/>
<xsl:template match="/*">
<Customers>
<xsl:for-each-group select="CustomerStatement" group-by="ID">
<Customer>
<xsl:copy-of select="current-group()[1]/Name|current-group()[1]/ID" />
<Amounts>
<xsl:for-each select="current-group()/Amt">
<Amount>
<xsl:apply-templates />
</Amount>
</xsl:for-each>
</Amounts>
</Customer>
</xsl:for-each-group>
</Customers>
</xsl:template>
</xsl:stylesheet>
In this case, notice XSLT 2.0's use of the for-each-group element, which eliminates the need for the sometimes-verbose and potentially confusing Muenchian Grouping method.