Question

I am trying to write a loop using XSLT so that it automatically groups all items with the same ID but in a case insensitive way. Unfortunately the data that I am trying to parse through is client driven so I cannot change it prior to load.
regardless here is a XML structure…

<Document>
    <Row>
        <Cell>ID</Cell>
    </Row>
    <Row>
        <Cell>hi</Cell>
    </Row>
    <Row>
        <Cell>Hi</Cell>
    </Row>
    <Row>
        <Cell>Hello</Cell>
    </Row>
    <Row>
        <Cell>Hello</Cell>
    </Row>
    <Row>
        <Cell>Hola</Cell>
    </Row>
</Document>

This is the XSLT I am currently using…

  <xsl:template match="Document">
    <NewDocument xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
      <xsl:for-each select="//Row[position() &gt; 1]/Cell[1][not(.=preceding::Row/Cell[1])]">
        <xsl:variable name="currentOrderID" select="." />
        <xsl:variable name="currentOrderGroup" select="//Row[Cell[1] = $currentOrderID]" />

        <MainID>
          <xsl:value-of select="$currentOrderGroup[1]/Cell[1]"/>
        </MainID>
        <IDs>
          <xsl:for-each select="$currentOrderGroup">
            <id>
              <xsl:value-of select="Cell[1]"/>
            </id>
          </xsl:for-each>
        </IDs>
      </xsl:for-each>
    </NewDocument>
  </xsl:template>

This is just wrapping up things as expected in a CaSe SeNSiTiVe way…
I’ve been trying to use a translate in there in order to make everything uppercase, however I can’t seem to get the syntax just right.

The result I am trying to achieve here is this:

<NewDocument>
  <MainID>hi</MainID>
  <IDs>
    <id>hi</id>
    <id>Hi</id>
  </IDs>  
  <MainID>Hello</MainID>
  <IDs>
    <id>Hello</id>
    <id>Hello</id>
  </IDs>
  <MainID>Hola</MainID>
  <IDs>
    <id>Hola</id>
  </IDs>
</NewDocument>

Can’t seem to find anything specifically for what I need.
Thanks!

Answer 1

In XSLT1.0, to convert strings to lower case you need to use the rather cumbersome translate function in xpath.

translate(., 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', 'abcdefghijklmnopqrstuvwxyz')

Furthermore, your problem is one of grouping, and in XSLT1.0 that usually means a technique known as Meunchian Grouping. To do, this you first define a key to look up items in the groups you require

<xsl:key 
   name="Cell" 
   match="Cell" 
   use="translate(., 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', 'abcdefghijklmnopqrstuvwxyz')"/>

Here we are looking up cells based on their (lower-case) text content.

To find the first element in each group, you look for Cell elements in the XML which also happen to be the first element occurring in your look-up key

<xsl:apply-templates 
   select="Row/Cell
   [generate-id() 
    = generate-id(
       key('Cell', 
         translate(., 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', 'abcdefghijklmnopqrstuvwxyz'))[1])]"/>

Then, when you match the first element, you can then match all elements within the group by looking at the key.

Here is the full XSLT

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
   <xsl:key name="Cell" match="Cell" use="translate(., 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', 'abcdefghijklmnopqrstuvwxyz')"/>

   <xsl:template match="Document">
      <NewDocument>
         <xsl:apply-templates select="Row/Cell[generate-id() = generate-id(key('Cell', translate(., 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', 'abcdefghijklmnopqrstuvwxyz'))[1])]"/>
      </NewDocument>
   </xsl:template>

   <xsl:template match="Cell">
      <MainID>
         <xsl:value-of select="."/>
      </MainID>
      <IDs>
         <xsl:apply-templates select="key('Cell', translate(., 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', 'abcdefghijklmnopqrstuvwxyz'))" mode="group"/>
      </IDs>
   </xsl:template>

   <xsl:template match="Cell" mode="group">
      <id>
         <xsl:value-of select="."/>
      </id>
   </xsl:template>
</xsl:stylesheet>

Note the use of the mode attribute, to distinguish between the two templates matching Cell elements.

When applied to your XML, the following is output:

<NewDocument>
   <MainID>ID</MainID>
   <IDs>
      <id>ID</id>
   </IDs>
   <MainID>hi</MainID>
   <IDs>
      <id>hi</id>
      <id>Hi</id>
   </IDs>
   <MainID>Hello</MainID>
   <IDs>
      <id>Hello</id>
      <id>Hello</id>
   </IDs>
   <MainID>Hola</MainID>
   <IDs>
      <id>Hola</id>
   </IDs>
</NewDocument>

Note, I wasn’t sure what to do with the Cell with ID as a value, so I left that it in. If you do want to exclude it, just add this line to the XSLT

<xsl:template match="Cell[. = 'ID']" />