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.