Need to merge 2 xml in xslt based on a common key - xslt

Question

I have 2 source variables which need to be merged based on a common key in XSLT
Variable 1:I have added few properties for each employee.
<EmpDetails>
<Emp>
<ID>1</ID>
<Name>A</Name>
<Address>abc 123</Address>
<Contact>1234567890</Contact>
<DOB>01/01/1989</DOB>
<Emp>
<Emp>
<ID>2</ID>
<Name>B</Name>
<Address>ASDF</Address>
<Contact>123456</Contact>
<DOB>02/02/1990</DOB>
<Emp>
</EmpDetails>
Variable 2:
<EmpAgeDetails>
<EmpAge>
<ID>1</ID>
<Age>27</Age>
<EmpAge>
<EmpAge>
<ID>2</ID>
<Age>26</Age>
<EmpAge>
</EmpAgeDetails>
Expected output:
<EmpDetails>
<Emp>
<ID>1</ID>
<Name>A</Name>
<Address>abc 123</Address>
<Contact>1234567890</Contact>
<DOB>01/01/1989</DOB>
<Age>27</Age>
<Emp>
<Emp>
<ID>2</ID>
<Name>B</Name>
<Address>ASDF</Address>
<Contact>123456</Contact>
<DOB>02/02/1990</DOB>
<Age>26</Age>
<Emp>
</EmpDetails>
I am using a template to copy all elements from Variable 1 which is working fine.
But now I need to merge that extra element of Age.
Any help is appreciated

Answer 1

Using XSLT 3.0 and xsl:merge, as supported in the latest Altova XMLSpy/Raptor or Saxon 9.7 EE, you can use
<xsl:stylesheet version="3.0" 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" xmlns:math="http://www.w3.org/2005/xpath-functions/math" xmlns:array="http://www.w3.org/2005/xpath-functions/array" xmlns:map="http://www.w3.org/2005/xpath-functions/map" exclude-result-prefixes="array fn map math xs">
<xsl:mode on-no-match="shallow-copy"/>
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
<xsl:param name="doc1">
<EmpDetails>
<Emp>
<ID>1</ID>
<Name>A</Name>
<Address>abc 123</Address>
<Contact>1234567890</Contact>
<DOB>01/01/1989</DOB>
</Emp>
<Emp>
<ID>2</ID>
<Name>B</Name>
<Address>ASDF</Address>
<Contact>123456</Contact>
<DOB>02/02/1990</DOB>
</Emp>
</EmpDetails>
</xsl:param>
<xsl:param name="doc2">
<EmpAgeDetails>
<EmpAge>
<ID>1</ID>
<Age>27</Age>
</EmpAge>
<EmpAge>
<ID>2</ID>
<Age>26</Age>
</EmpAge>
</EmpAgeDetails>
</xsl:param>
<xsl:template match="/" name="xsl:initial-template">
<EmpDetails>
<xsl:merge>
<xsl:merge-source select="$doc1/EmpDetails/Emp">
<xsl:merge-key select="ID"></xsl:merge-key>
</xsl:merge-source>
<xsl:merge-source select="$doc2/EmpAgeDetails/EmpAge">
<xsl:merge-key select="ID"></xsl:merge-key>
</xsl:merge-source>
<xsl:merge-action>
<xsl:copy>
<xsl:apply-templates select="current-merge-group()[1]/*, fn:current-merge-group()[2]/Age"/>
</xsl:copy>
</xsl:merge-action>
</xsl:merge>
</EmpDetails>
</xsl:template>
</xsl:stylesheet>
Using XSLT 2.0 you could group:
<?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:param name="doc1">
<EmpDetails>
<Emp>
<ID>1</ID>
<Name>A</Name>
<Address>abc 123</Address>
<Contact>1234567890</Contact>
<DOB>01/01/1989</DOB>
</Emp>
<Emp>
<ID>2</ID>
<Name>B</Name>
<Address>ASDF</Address>
<Contact>123456</Contact>
<DOB>02/02/1990</DOB>
</Emp>
</EmpDetails>
</xsl:param>
<xsl:param name="doc2">
<EmpAgeDetails>
<EmpAge>
<ID>1</ID>
<Age>27</Age>
</EmpAge>
<EmpAge>
<ID>2</ID>
<Age>26</Age>
</EmpAge>
</EmpAgeDetails>
</xsl:param>
<xsl:template match="/" name="main">
<EmpDetails>
<xsl:for-each-group select="$doc1/EmpDetails/Emp, $doc2/EmpAgeDetails/EmpAge" group-by="ID">
<xsl:copy>
<xsl:copy-of select="current-group()[1]/*, current-group()[2]/Age"/>
</xsl:copy>
</xsl:for-each-group>
</EmpDetails>
</xsl:template>
</xsl:stylesheet>