Conditional grouping in XSLT - xpath

Question

Request your help to transform XML using XSLT 2
My input XML looks like below.
<?xml version="1.0" encoding="UTF-8"?>
<Workers>
<Worker>
<Batch_number>1234</Batch_number>
<Name>David</Name>
<Assignment>
<type>A</type>
<name>New York</name>
</Assignment>
</Worker>
<Worker>
<Batch_number>1234</Batch_number>
<Name>David</Name>
<Assignment>
<type>B</type>
<name>Boston</name>
</Assignment>
</Worker>
<Worker>
<Batch_number>1234</Batch_number>
<Name>David</Name>
<Assignment>
<type>C</type>
<name>Chicago</name>
</Assignment>
</Worker>
<Worker>
<Batch_number>78698</Batch_number>
<Name>Karen</Name>
<Assignment>
<type>C</type>
<name>Chicago</name>
</Assignment>
</Worker>
</Workers>
Desired output looks like below.
<?xml version="1.0" encoding="UTF-8"?>
<Worker>
<Batch_number>1234</Batch_number>
<Name>David</Name>
<Assignment>
<type>A</type>
<name>New York</name>
</Assignment>
<Assignment>
<type>B</type>
<name>Boston</name>
</Assignment>
<Assignment>
<type>C</type>
<name>Chicago</name>
</Assignment>
</Worker>
<Worker>
<Batch_number>78698</Batch_number>
<Name>Karen</Name>
<Assignment>
<type>C</type>
<name>Chicago</name>
</Assignment>
</Worker>
Condition for transformation is:
If child node <Worker>with same <Batch_number>exists in input file, all Assignment nodes for same <Batch_number> should be grouped together under one Worker child node right after <Batch_number> and <Name>
Can someone help me write the correct code to achieve this please?

Answer 1

Although your desired output XML is not well-formed, here is an XSLT-2.0 solution which suffices your special needs:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" indent="yes"/>
<xsl:template match="/Workers">
<xsl:for-each-group select="Worker" group-by="Batch_number">
<Worker>
<Batch_number><xsl:value-of select="current-grouping-key()" /></Batch_number>
<Name><xsl:value-of select="current()/Name" /></Name>
<xsl:copy-of select="current-group()/Assignment" />
</Worker>
</xsl:for-each-group>
</xsl:template>
</xsl:stylesheet>
Its output is:
<?xml version="1.0" encoding="UTF-8"?>
<Worker>
<Batch_number>1234</Batch_number>
<Name>David</Name>
<Assignment>
<type>A</type>
<name>New York</name>
</Assignment>
<Assignment>
<type>B</type>
<name>Boston</name>
</Assignment>
<Assignment>
<type>C</type>
<name>Chicago</name>
</Assignment>
</Worker>
<Worker>
<Batch_number>78698</Batch_number>
<Name>Karen</Name>
<Assignment>
<type>C</type>
<name>Chicago</name>
</Assignment>
</Worker>