Merging tags based on two different complex tags

Question

In the below two ASNInPO's po_nbr is same container_id under ASNInCtn is same and item_id under ASNInItem is different. In this case two ASNInPO's has to be merged and two ASNInCtn's has to be merged into one tag. This is my Input:

     <?xml version = '1.0' encoding = 'UTF-8'?>
 <ASNInDesc>
    <asn_nbr>ASN-1</asn_nbr>
    <ASNInPO>
      <po_nbr>PO-2</po_nbr>
      <ASNInCtn>
         <container_id>CONTAINER-2</container_id>
         <ASNInItem>
            <item_id>ITEM-2</item_id>
            <unit_qty>3</unit_qty>
         </ASNInItem>
      </ASNInCtn>
   </ASNInPO>
   <ASNInPO>
      <po_nbr>PO-2</po_nbr>
      <ASNInCtn>
         <container_id>CONTAINER-2</container_id>
         <ASNInItem>
            <item_id>ITEM-3</item_id>
            <unit_qty>3</unit_qty>
         </ASNInItem>
      </ASNInCtn>
   </ASNInPO>
  </ASNInDesc>

This is the desired output:

<?xml version = '1.0' encoding = 'UTF-8'?>
 <ASNInDesc>
    <asn_nbr>ASN-1</asn_nbr>
    <ASNInPO>
      <po_nbr>PO-2</po_nbr>
      <ASNInCtn>
         <container_id>CONTAINER-2</container_id>
         <ASNInItem>
            <item_id>ITEM-2</item_id>
            <unit_qty>3</unit_qty>
         </ASNInItem>
         <ASNInItem>
            <item_id>ITEM-3</item_id>
            <unit_qty>3</unit_qty>
         </ASNInItem>        
      </ASNInCtn>
   </ASNInPO>
 </ASNInDesc>

Please help me in solving this.

Answer 1

Since this question is tagged with xslt-1.0, I'll post a XSLT 1.0 solution using the Muenchian grouping method. (Perhaps someone else will contribute a XSLT 2.0 solution. It might be instructive to compare them.)

Let's walk through the stylesheet.

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

Grouping 1: ASNInPO elements by po_nbr

Since we want to group ASNInPO elements by their po_nbr, let's start by defining a key which allows retrieving ASNInPO elements by their po_nbr value.

  <xsl:key name="ASNInPO-by-po_nbr" 
           match="ASNInPO" use="po_nbr"/>

Then we'll write a template which matches an ASNInDesc. We'll make a copy of the element, along with its asn_nbr. Now we want to group the contained ASNInPO elements by their po_nbr. We do this by applying templates to the first ASNInPo in each group:

  <xsl:template match="ASNInDesc">
    <xsl:copy>
      <xsl:copy-of select="asn_nbr"/>
      <xsl:apply-templates select="ASNInPO[generate-id() =
                                   generate-id(key('ASNInPO-by-po_nbr', 
                                                   po_nbr)[1])]"/>
    </xsl:copy>
  </xsl:template>

Grouping 2: ASNInCtn elements by container_id

But before we go further, we'll need to define another key. It seems like we need to group ASNInCtn elements by their container_id (see note below if this is not the case).

  <xsl:key name="ASNInCtn-by-container_id" 
           match="ASNInCtn" use="container_id"/>

We'll need that key in the following template which matches ASNInPO elements. Remember that the elements we process here will be the first ones of their group, since we selected only those in the xsl:apply-template above.

This template is similar to the one we wrote above. We make copy of the element itself along with its po_nbr and then again apply templates to the first ASNInCtn elements grouped by their container_id:

  <xsl:template match="ASNInPO">
    <xsl:copy>
      <xsl:copy-of select="po_nbr"/>
      <xsl:apply-templates select="key('ASNInPO-by-po_nbr', po_nbr)/
                                   ASNInCtn[generate-id() =
                                   generate-id(key('ASNInCtn-by-container_id',
                                                   container_id)[1])]"/>
    </xsl:copy>
  </xsl:template>

Finally, we write the template which matches ASNInCtn elements. This copies the element itself, and its container_id and then copies all ASNInItem elements in the same group:

  <xsl:template match="ASNInCtn">
    <xsl:copy>
      <xsl:copy-of select="container_id"/>
      <xsl:copy-of select="key('ASNInCtn-by-container_id', 
                               container_id)/ASNInItem"/>
    </xsl:copy>
  </xsl:template>

And we're done.

</xsl:stylesheet>

Note

The solution assumes that the ASNInCtn element with a given container_id can only appear within ASNInPO elements with the same po_nbr. If this is not the case, then you need to adjust the key for ASNInPO objects to use a combination of po_nbr and container_id.