XSLT Mapping to copy all nodes but modify one node

user_15969403 0
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I am relatively new to XSLT and have a requirement. Below is my input XML

<Response>
    <STF_N>123</STF_N>
    <STF_1NM_T>Moon Go</STF_1NM_T>
    <STF_SURNM_T>Kimm</STF_SURNM_T>
    <STF_FULLNM_T>Kimm Moon Go</STF_FULLNM_T>
    <STF_HIRE_D>1990-06-25T00:00:00.000</STF_HIRE_D>
    <APPT_ID>A</APPT_ID>
</Response>
<Response>
    <STF_N>123</STF_N>
    <STF_1NM_T>Moon Go</STF_1NM_T>
    <STF_SURNM_T>Kimm</STF_SURNM_T>
    <STF_FULLNM_T>Kimm Moon Go</STF_FULLNM_T>
    <STF_HIRE_D>2020-06-25T00:00:00.000</STF_HIRE_D>
    <APPT_ID>B</APPT_ID>
</Response>

Required output -

<Response>
    <STF_N>123</STF_N>
    <STF_1NM_T>Moon Go</STF_1NM_T>
    <STF_SURNM_T>Kimm</STF_SURNM_T>
    <STF_FULLNM_T>Kimm Moon Go</STF_FULLNM_T>
    <STF_HIRE_D>1990-06-25T00:00:00.000</STF_HIRE_D>
    <APPT_ID>A</APPT_ID>
</Response>
<Response>
    <STF_N>123</STF_N>
    <STF_1NM_T>Moon Go</STF_1NM_T>
    <STF_SURNM_T>Kimm</STF_SURNM_T>
    <STF_FULLNM_T>Kimm Moon Go</STF_FULLNM_T>
    <STF_HIRE_D>1990-06-25T00:00:00.000</STF_HIRE_D>
    <APPT_ID>B</APPT_ID>
</Response>

The STF_HIRE_D should be the same (first value) for all records with the same STF_N.

I used the below XSLT but it is not working as expected -

<xsl:output indent="yes"/>
<xsl:template match="@*|node()">
    <xsl:copy>
        <xsl:apply-templates select="@*|node()"/>
    </xsl:copy>
</xsl:template>

<xsl:template match="Response/STF_HIRE_D">
              <xsl:for-each-group select="Response" group-by="STF_N">
              <STF_HIRE_D>
                  <xsl:value-of select="current-group()[1]/STF_HIRE_D"/>
              </STF_HIRE_D> 
              </xsl:for-each-group>

Any help is much appreciated.

Thank you

xslt xml
2 Answers

It is also possible to use a key and simply pull in the necessary value based on node identity:

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  version="3.0"
  xmlns:xs="http://www.w3.org/2001/XMLSchema"
  exclude-result-prefixes="#all"
  expand-text="yes">

  <xsl:key name="stf_n" match="Response" use="STF_N"/>
  
  <xsl:mode on-no-match="shallow-copy"/>
  
  <xsl:template match="Response[not(. is key('stf_n', STF_N)[1])]/STF_HIRE_D">
    <xsl:copy>{key('stf_n', ../STF_N)[1]/STF_HIRE_D}</xsl:copy>
  </xsl:template>

</xsl:stylesheet>

If you work with an XSLT 2 instead of an XSLT 3 processor you can declare <xsl:mode on-no-match="shallow-copy"/> but would keep your template

<xsl:template match="@*|node()">
    <xsl:copy>
        <xsl:apply-templates select="@*|node()"/>
    </xsl:copy>
</xsl:template>

instead. The key works as well in XSLT 2 as in XSLT 3.

Instead of a key in XSLT 3 you could also use an accumulator to store the value pair (STF_N, STF_HIRE_D) in a map:

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  version="3.0"
  xmlns:xs="http://www.w3.org/2001/XMLSchema"
  xmlns:map="http://www.w3.org/2005/xpath-functions/map"
  exclude-result-prefixes="#all"
  expand-text="yes">

  <xsl:accumulator name="hire-date" as="map(xs:string, xs:string)" initial-value="map{}">
    <xsl:accumulator-rule match="Response/STF_HIRE_D"
      select="if (map:contains($value, ../STF_N/string()))
              then $value
              else map:put($value, ../STF_N/string(), string())"/>
  </xsl:accumulator>
  
  <xsl:mode on-no-match="shallow-copy" use-accumulators="hire-date"/>
  
  <xsl:template match="Response/STF_HIRE_D">
    <xsl:copy>{accumulator-before('hire-date')(../STF_N/string())}</xsl:copy>
  </xsl:template>

</xsl:stylesheet>

Finally, using streaming you could use two accumulators, one to keep track of the STF_N value inside of a Response element, the other to store the STF_N -> STF_HIRE_D:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  version="3.0"
  xmlns:xs="http://www.w3.org/2001/XMLSchema"
  xmlns:map="http://www.w3.org/2005/xpath-functions/map"
  exclude-result-prefixes="#all"
  expand-text="yes">
  
  <xsl:accumulator name="stf_n" as="xs:string?" initial-value="()" streamable="yes">
    <xsl:accumulator-rule match="Response/STF_N/text()" select="string()"/>
    <xsl:accumulator-rule phase="end" match="Response" select="()"/>
  </xsl:accumulator>

  <xsl:accumulator name="hire-date" as="map(xs:string, xs:string)" initial-value="map{}" streamable="yes">
    <xsl:accumulator-rule match="Response/STF_HIRE_D/text()"
      select="if (map:contains($value, accumulator-before('stf_n')))
              then $value
              else map:put($value, accumulator-before('stf_n'), string())"/>
  </xsl:accumulator>
  
  <xsl:mode streamable="yes" on-no-match="shallow-copy" use-accumulators="stf_n hire-date"/>
  
  <xsl:template match="Response/STF_HIRE_D/text()">
    <xsl:copy>{accumulator-before('hire-date')(accumulator-before('stf_n'))}</xsl:copy>
  </xsl:template>

</xsl:stylesheet>

That way and with Saxon EE which supports streaming in XSLT 3, you could process huge documents without parsing the whole XML document in an XDM tree.

user_2522280

For this you could use a tunnel-parameter.

Using this source xml with one root-element:

<?xml version='1.0' encoding='UTF-8'?>
<Responses>
  <Response>
    <STF_N>123</STF_N>
    <STF_1NM_T>Moon Go</STF_1NM_T>
    <STF_SURNM_T>Kimm</STF_SURNM_T>
    <STF_FULLNM_T>Kimm Moon Go</STF_FULLNM_T>
    <STF_HIRE_D>1990-06-25T00:00:00.000</STF_HIRE_D>
    <APPT_ID>A</APPT_ID>
  </Response>
  <Response>
    <STF_N>123</STF_N>
    <STF_1NM_T>Moon Go</STF_1NM_T>
    <STF_SURNM_T>Kimm</STF_SURNM_T>
    <STF_FULLNM_T>Kimm Moon Go</STF_FULLNM_T>
    <STF_HIRE_D>2020-06-25T00:00:00.000</STF_HIRE_D>
    <APPT_ID>B</APPT_ID>
  </Response>  
</Responses>

Using this xslt:

<?xml version='1.0' encoding='UTF-8'?>
<xsl:stylesheet 
  version="2.0" 
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
  exclude-result-prefixes="#all">

  <xsl:output indent="yes"/>
  <xsl:template match="@*|node()">
    <xsl:copy>
      <xsl:apply-templates select="@*|node()"/>
    </xsl:copy>
  </xsl:template>
  
  <xsl:template match="Responses">
    <xsl:copy>
      <xsl:for-each-group select="Response" group-by="STF_N">
      <xsl:apply-templates select="current-group()">
        <xsl:with-param name="hireDate" select="current-group()[1]/STF_HIRE_D" tunnel="yes"/>
      </xsl:apply-templates>
    </xsl:for-each-group>
    </xsl:copy>
  </xsl:template>

  <xsl:template match="STF_HIRE_D">
    <xsl:param name="hireDate" tunnel="yes"/>
    <xsl:copy>
      <xsl:value-of select="$hireDate"/>
    </xsl:copy>
  </xsl:template>
  
</xsl:stylesheet>

Will give the expected result (also with one root-element)

<?xml version="1.0" encoding="UTF-8"?>
<Responses>
   <Response>
      <STF_N>123</STF_N>
      <STF_1NM_T>Moon Go</STF_1NM_T>
      <STF_SURNM_T>Kimm</STF_SURNM_T>
      <STF_FULLNM_T>Kimm Moon Go</STF_FULLNM_T>
      <STF_HIRE_D>1990-06-25T00:00:00.000</STF_HIRE_D>
      <APPT_ID>A</APPT_ID>
   </Response>
   <Response>
      <STF_N>123</STF_N>
      <STF_1NM_T>Moon Go</STF_1NM_T>
      <STF_SURNM_T>Kimm</STF_SURNM_T>
      <STF_FULLNM_T>Kimm Moon Go</STF_FULLNM_T>
      <STF_HIRE_D>1990-06-25T00:00:00.000</STF_HIRE_D>
      <APPT_ID>B</APPT_ID>
   </Response>
</Responses>
user_37100530
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