how to check duplicate element values using xslt

Question

    <BookList>
    <Book>
    <History>
    <Type>history</Type>
    <Prize>123</Prize>
    <Publication>``
    <Name>YEAP1</Name>
    </Publication>
    <RNumber Type="VolumeNumber">11111</RNumber>
    <RNumber Type="SupplementNumber">123456</RNumber>
    </History>
    <chemistry>
    <Type>chemistry</Type>
    <Prize>333</Prize>
    <Publication>
    <Name>YEAP</Name>
    </Publication>
    <RNumber Type="VolumeNumber">11111</RNumber>
    <RNumber Type="SupplementNumber">45454</RNumber>
    </chemistry>
                      ......

    </Book>
    </BookList>

There are duplicate VolumnNumber 11111. How to check duplicate VolumnNumber in BoolList xml using xslt . please help on this

Possible duplicate with: stackoverflow.com/questions/157705/… — David Brabant
– David Brabant, Commented Apr 18, 2012 at 18:56
Are you just trying to check to see if there is a duplicate? What is the expected output supposed to look like? (ie, an html page that displays which volumes are duplicates?) — javram
– javram, Commented Apr 18, 2012 at 19:05
need to check is there any duplicate volumnnumber exist in xml or not — Sanjay Sanjay
– Sanjay Sanjay, Commented Apr 18, 2012 at 19:07

Dimitre Novatchev · Accepted Answer · 2012-04-18 22:43:12Z

2

I. This can be found using a single XPath expression:

    false()
   or
    /*/*/*/RNumber
           [@Type='VolumeNumber'
          and
            . = ../preceding-sibling::*
                   /RNumber[@Type='VolumeNumber']
            ]

Here is a complete XSLT transformation that evaluates this XPath expression and outputs the result of this evaluation:

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>

 <xsl:template match="/">
  Duplicate volume numbers exist: <xsl:text/>

  <xsl:value-of select=
   "false()
   or
    /*/*/*/RNumber
           [@Type='VolumeNumber'
          and
            . = ../preceding-sibling::*
                   /RNumber[@Type='VolumeNumber']
            ]
   "/>

 </xsl:template>
</xsl:stylesheet>

When this transformation is applied on the provided XML document:

<BookList>
    <Book>
        <History>
            <Type>history</Type>
            <Prize>123</Prize>
            <Publication>``     
                <Name>YEAP1</Name>
            </Publication>
            <RNumber Type="VolumeNumber">11111</RNumber>
            <RNumber Type="SupplementNumber">123456</RNumber>
        </History>
        <chemistry>
            <Type>chemistry</Type>
            <Prize>333</Prize>
            <Publication>
                <Name>YEAP</Name>
            </Publication>
            <RNumber Type="VolumeNumber">11111</RNumber>
            <RNumber Type="SupplementNumber">45454</RNumber>
        </chemistry>
        ......      
    </Book>
</BookList>

the wanted, correct result is produced:

  Duplicate volume numbers exist: true

II. Solution using keys (generally more efficient):

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>

  <xsl:key name="kVolNum" match="RNumber[@Type='VolumeNumber']"
          use="."/>

 <xsl:template match="/">
  Duplicate volume numbers exist: <xsl:text/>

  <xsl:value-of select=
   "false()
   or
    /*/*/*/RNumber
            [@Type='VolumeNumber'
           and
             key('kVolNum',.)[2]
            ]"/>

 </xsl:template>
</xsl:stylesheet>

When this transformation is applied on the same XML document (above), the same correct result is produced:

  Duplicate volume numbers exist: true

edited Apr 18, 2012 at 22:43

answered Apr 18, 2012 at 22:34

Dimitre Novatchev

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2 Comments

Alex S Over a year ago

Long time since 2003/04/05 on XSL List - Just playing after a decade - If I wanted to check if there were any duplicates of <string>com.text1.text2</string> thru an XML file at any level, will this still work or should I post a fresh question?

Alex S Over a year ago

E.g. Here - stackoverflow.com/questions/43730689/…

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