xslt 1.0 xml merging between 2 nodes

Question

could you please help me on this one? I've been trying to merge 2 xml node based on key in xslt 1.0, but I'm not getting anywhere unfortunately.

This is the XML input:

<?xml version="1.0" encoding="UTF-8"?>
<csv>
   <line>
      <field>DE</field>
      <field/>
      <field>DE:STN</field>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
   </line>
   <line>
      <field>DE</field>
      <field>DE:MWST</field>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
   </line>
   <line>
      <field>SI</field>
      <field/>
      <field>SI:MSPRS</field>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
   </line>

   <line>
      <field>BE</field>
      <field>BE:BTW</field>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
   </line>
</csv>

And I should have the following XML output in merging the lines which have the same line/field[1] as key, but very important preserving the order of values for line/field[i] between the lines:

<?xml version="1.0" encoding="UTF-8"?>
<csv>
   <line>
      <field>DE</field>
      <field>DE:MWST</field>
      <field>DE:STN</field>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
   </line>
   <line>
      <field>SI</field>
      <field/>
      <field>SI:MSPRS</field>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
   </line>

   <line>
      <field>BE</field>
      <field>BE:BTW</field>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
      <field/>
   </line>
</csv>

If you could please give me a hint on how to solve this it would be great:)! Thank you very much!

Answer 1

Try the following stylesheet. It uses the Muenchian method to group the line s by the value of the first field , then populates each field with the value of the first field of the group in the same position that has a string value.

XSLT 1.0

<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:key name="line" match="line" use="field[1]" />

<xsl:template match="/csv">
    <xsl:copy>
        <xsl:for-each select="line[count(. | key('line', field[1])[1]) = 1]">
            <xsl:copy>
                <xsl:variable name="current-group" select="key('line', field[1])" />
                <xsl:for-each select="field">
                    <xsl:variable name="i" select="position()" />
                    <xsl:copy>  
                        <xsl:value-of select="$current-group/field[$i][string()]"/>
                    </xsl:copy>
                </xsl:for-each>
            </xsl:copy>
        </xsl:for-each>
    </xsl:copy>
</xsl:template>

</xsl:stylesheet>