XSL - remove the duplicate node but keep the original

Question

Need help in removing the duplicate node from the input xml using XSLT

This is how my XML looks like,

<?xml version="1.0"?>

<NodeA NodeAattr="123">

<NodeB NodeBattr="456"></NodeB>

<NodeC>
    <NodeD="ValueD">
       <NodeE Name="ValueABC">
          <NodeF Value="0"></NodeF >
       </NodeE >
       <NodeE Name="ValueABC">
          <NodeF Value="0"></NodeF >
       </NodeE>
  </NodeD>
</NodeC>
</NodeA>

My final output should look like

<NodeA NodeAattr="123">

<NodeB NodeBattr="456"></NodeB>

<NodeC>
    <NodeD="ValueD">
       <NodeE Name="ValueABC">
          <NodeF Value="0"></NodeF>
       </NodeE >
    </NodeD>
</NodeC>
</NodeA>

Here the Name attribute of Node E has duplicate values. Based on this attribute I need to eliminate the duplicate.

It would be really helpful if someone could help me with the XSLT required here to get the output. I can only use the XSLT 1.0

Will the duplicate elements always have the same parent element? If two NodeE elements have the same name, but different parents, does that count as duplicates? — Tim C, Apr 10 '13 at 12:30
@Tim C Yes, the duplicate elements will have the same parent — arulapp, Apr 11 '13 at 08:33

score 1 · Answer 1 · answered Apr 10 '13 at 13:03

If two <NodeE> elements are considered duplicates only if they have the same parent, this is probably the simplest solution:

Input

<?xml version="1.0"?>

<NodeA NodeAattr="123">

  <NodeB NodeBattr="456"></NodeB>

  <NodeC>
    <NodeD Name="ValueD">
      <NodeE Name="ValueABC">
        <NodeF Value="0"></NodeF>
      </NodeE>
      <NodeE Name="ValueABC">
        <NodeF Value="0"></NodeF>
      </NodeE>
    </NodeD>
    <!-- Added another <NodeD> element for demonstration -->
    <NodeD>
      <NodeE Name="ValueABC">
        <NodeF Value="0"></NodeF>
      </NodeE>
      <NodeE Name="ValueDEF">
        <NodeF Value="0"></NodeF>
      </NodeE>
    </NodeD>
  </NodeC>
</NodeA>

Stylesheet #1

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="xml" version="1.0" encoding="utf-8" indent="yes"/>
  <xsl:strip-space elements="*"/>

  <!--
  Identity transform: copy elements and attributes from input file as is
  -->
  <xsl:template match="node() | @*">
    <xsl:copy>
      <xsl:apply-templates select="node() | @*"/>
    </xsl:copy>
  </xsl:template>

  <!--
  Drop <NodeE> elements with a preceding <NodeE> sibling that has the same
  @Name attribute value as the current element
  -->
  <xsl:template
    match="NodeE[preceding-sibling::NodeE[@Name = current()/@Name]]"/>

</xsl:stylesheet>

Output #1

<?xml version="1.0" encoding="utf-8"?>
<NodeA NodeAattr="123">
  <NodeB NodeBattr="456"/>
  <NodeC>
    <NodeD Name="ValueD">
      <NodeE Name="ValueABC">
        <NodeF Value="0"/>
      </NodeE>
    </NodeD>
    <NodeD>
      <NodeE Name="ValueABC">
        <NodeF Value="0"/>
      </NodeE>
      <NodeE Name="ValueDEF">
        <NodeF Value="0"/>
      </NodeE>
    </NodeD>
  </NodeC>
</NodeA>

On the other hand, if <NodeE> elements should be considered duplicates across the whole document, you can use Muenchian grouping:

Stylesheet #2

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="xml" version="1.0" encoding="utf-8" indent="yes"/>
  <xsl:strip-space elements="*"/>

  <xsl:key name="kNode" match="NodeE" use="@Name"/>

  <!--
  Identity transform: copy elements and attributes from input file as is
  -->
  <xsl:template match="node() | @*">
    <xsl:copy>
      <xsl:apply-templates select="node() | @*"/>
    </xsl:copy>
  </xsl:template>

  <!--
  Use Muenchian grouping to apply unique NodeE elements.
  See http://www.jenitennison.com/xslt/grouping/muenchian.html
  -->
  <xsl:template match="NodeE[generate-id() = 
                       generate-id(key('kNode', @Name)[1])]">
    <xsl:copy>
      <xsl:apply-templates select="node() | @*"/>
    </xsl:copy>
  </xsl:template>

  <!-- Drop other <NodeE> elements -->
  <xsl:template match="NodeE"/>

</xsl:stylesheet>

Output #2

<?xml version="1.0" encoding="utf-8"?>
<NodeA NodeAattr="123">
  <NodeB NodeBattr="456"/>
  <NodeC>
    <NodeD Name="ValueD">
      <NodeE Name="ValueABC">
        <NodeF Value="0"/>
      </NodeE>
    </NodeD>
    <NodeD>
      <NodeE Name="ValueDEF">
        <NodeF Value="0"/>
      </NodeE>
    </NodeD>
  </NodeC>
</NodeA>

@ Eero It works like a charm. Thanks a ton. But I have one more question in mind. For instance, if I want to remove only the duplicate node whose 'Name' attribute value is "ValueABC", how this will be restructured? I dont want to touch the other nodes whose 'Name' attributes' values are "ValueDEF", "ValueGHJ" — arulapp, Apr 11 '13 at 08:43
For stylesheet #1, the change is pretty simple, just add a predicate to narrow down the node set: ``. For #2, you could do something [like this](https://gist.github.com/anonymous/5362145). There might be a simpler solution for #2, but that's what popped into my mind first. — Eero Helenius, Apr 11 '13 at 09:58
On a similar note, could you provide me with your comments on this one as well ? http://stackoverflow.com/questions/16020026/xsl-combining-values-of-siblings-if-values-of-an-attribute-is-same — arulapp, Apr 15 '13 at 16:24

score -1 · Answer 2 · answered Apr 10 '13 at 13:01

Use "deep-euql" function to compare two item(). Check this one:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:xs="http://www.w3.org/2001/XMLSchema">

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

  <xsl:template match="NodeE">
    <xsl:choose>
      <xsl:when test="deep-equal(self::NodeE, following-sibling::NodeE)"/>
      <xsl:otherwise>
        <xsl:copy>
          <xsl:apply-templates select="* | @*"/>
        </xsl:copy>
      </xsl:otherwise>
    </xsl:choose>
  </xsl:template>

</xsl:stylesheet>

@Peter is correct: `deep-equal()` is only available in XPath 2.0. — ABach, Apr 10 '13 at 15:14