Group-by two conditions in one element

Question

I am trying to group-by two conditions in one element, which practically means that machine and parts with same ID (before '-' should be grouped.

Input:

<Document>
    <DocumentLine>
        <ExternalBatchNo>KEC36770</ExternalBatchNo>
        <Attribute01>machine</Attribute01>
    </DocumentLine>
    <DocumentLine>
        <ExternalBatchNo>KEC36770-2</ExternalBatchNo>
        <Attribute01>part</Attribute01>
    </DocumentLine>
    <DocumentLine>
        <ExternalBatchNo>KEC36771</ExternalBatchNo>
        <Attribute01>machine</Attribute01>
    </DocumentLine>
    <DocumentLine>
        <ExternalBatchNo>KEC36771-2</ExternalBatchNo>
        <Attribute01>part</Attribute01>
    </DocumentLine>
    <DocumentLine>
        <ExternalBatchNo>KEC36771-3</ExternalBatchNo>
        <Attribute01>part</Attribute01>
    </DocumentLine>
</Document>

Expected result:

<Document>
    <DocumentLine>
        <ExternalBatchNo>KEC36770</ExternalBatchNo>
        <Attribute01>machine</Attribute01>
    </DocumentLine>
    <DocumentLine>
        <ExternalBatchNo>KEC36770-2</ExternalBatchNo>
        <Attribute01>part</Attribute01>
    </DocumentLine>
</Document>

<Document>
    <DocumentLine>
        <ExternalBatchNo>KEC36771</ExternalBatchNo>
        <Attribute01>machine</Attribute01>
    </DocumentLine>
    <DocumentLine>
        <ExternalBatchNo>KEC36771-2</ExternalBatchNo>
        <Attribute01>part</Attribute01>
    </DocumentLine>
    <DocumentLine>
        <ExternalBatchNo>KEC36771-3</ExternalBatchNo>
        <Attribute01>part</Attribute01>
    </DocumentLine>
</Document>

This is what I tried, but this results in an empty machine ID and so only groups on parts.

<xsl:for-each-group select="Message/Documents/Document/DocumentLine" group-by="substring-before(ExternalBatchNo,'-')">

So I am thinking about using some template where he should pick the ExternalBatchNo when value doesn't contain an '-'. But, how?

Answer 1

If you can use xslt version 2.0, you could use something like this:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet 
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  version="2.0">
  
  <xsl:output indent="yes"/>
  
  <xsl:strip-space elements="*"/>
  
  <xsl:template match="Documents">
    <xsl:copy>
      <!-- Your `substring-before` will not work on strings without the dash. Try tokenize instead -->
      <xsl:for-each-group select="Document/DocumentLine" group-by="tokenize(ExternalBatchNo,'-')[1]">
        <Document>
          <xsl:copy-of select="current-group()"/>
        </Document>
      </xsl:for-each-group>    
    </xsl:copy>
  </xsl:template>  

</xsl:stylesheet>

Using this source xml:

<?xml version="1.0" encoding="UTF-8"?>
<Message>
  <Documents>
    <Document>
      <DocumentLine>
        <ExternalBatchNo>KEC36770</ExternalBatchNo>
        <Attribute01>machine</Attribute01>
      </DocumentLine>
      <DocumentLine>
        <ExternalBatchNo>KEC36770-2</ExternalBatchNo>
        <Attribute01>part</Attribute01>
      </DocumentLine>
      <DocumentLine>
        <ExternalBatchNo>KEC36771</ExternalBatchNo>
        <Attribute01>machine</Attribute01>
      </DocumentLine>
      <DocumentLine>
        <ExternalBatchNo>KEC36771-2</ExternalBatchNo>
        <Attribute01>part</Attribute01>
      </DocumentLine>
      <DocumentLine>
        <ExternalBatchNo>KEC36771-3</ExternalBatchNo>
        <Attribute01>part</Attribute01>
      </DocumentLine>
    </Document>    
  </Documents>
</Message>

will give this result:

<?xml version="1.0" encoding="UTF-8"?>
<Documents>
   <Document>
      <DocumentLine>
         <ExternalBatchNo>KEC36770</ExternalBatchNo>
         <Attribute01>machine</Attribute01>
      </DocumentLine>
      <DocumentLine>
         <ExternalBatchNo>KEC36770-2</ExternalBatchNo>
         <Attribute01>part</Attribute01>
      </DocumentLine>
   </Document>
   <Document>
      <DocumentLine>
         <ExternalBatchNo>KEC36771</ExternalBatchNo>
         <Attribute01>machine</Attribute01>
      </DocumentLine>
      <DocumentLine>
         <ExternalBatchNo>KEC36771-2</ExternalBatchNo>
         <Attribute01>part</Attribute01>
      </DocumentLine>
      <DocumentLine>
         <ExternalBatchNo>KEC36771-3</ExternalBatchNo>
         <Attribute01>part</Attribute01>
      </DocumentLine>
   </Document>
</Documents>