Question

I need to use xsl/xpath (version 1.0) to do something special (for simplifying, say insert some dummy text) when the value of SupplierId changes. I need to handle 3 variations;

1. Do something when on the first Order (the first occurence of SupplierId)
2. Do somwthing when on OrderId O3 (SupplierId changed from S1 to S2)
3. Do something when on the last Order (the last occurence of SupplierId)

.

<?xml version='1.0' encoding='utf-8'?> <Orders>     <Order>         <OrderId>O1</OrderId>         <SupplierId>S1</SupplierId>     </Order>     <Order>         <OrderId>O2</OrderId>         <SupplierId>S1</SupplierId>     </Order>     <Order>         <OrderId>O3</OrderId>         <SupplierId>S2</SupplierId>     </Order>     <Order>         <OrderId>O4</OrderId>         <SupplierId>S2</SupplierId>     </Order>     <Order>         <OrderId>O5</OrderId>         <SupplierId>S2</SupplierId>     </Order> </Orders> 

I’ve tried using preceding-sibling, following-sibling, etc, but haven’t found out of it yet. I’d appreciate any help on this newbie question.

Wally

Answer 1

This is one natural and easy solution:

<xsl:stylesheet version='1.0'  xmlns:xsl='http://www.w3.org/1999/XSL/Transform'>  <xsl:output method='text'/>      <xsl:template match='Order[1]'>       First OrderId = <xsl:text/>       <xsl:value-of select='OrderId'/>     </xsl:template>      <xsl:template match='Order[last()]'>        Last OrderId = <xsl:text/>       <xsl:value-of select='OrderId'/>     </xsl:template>      <xsl:template match=       'Order[not(position() = 1)]          [not(SupplierId               =               preceding-sibling::Order[1]/SupplierId               )         ]'>        Changes in Order OrderId = <xsl:text/>       <xsl:value-of select='OrderId'/>          SupplierId = <xsl:text/>          <xsl:value-of select='SupplierId'/>       Previous Order OrderId = <xsl:text/>       <xsl:value-of select=         'preceding-sibling::Order[1]/OrderId'/>                  SupplierId = <xsl:text/>          <xsl:value-of select=          'preceding-sibling::Order[1]/SupplierId'/>     </xsl:template>      <xsl:template match='text()'/> </xsl:stylesheet> 

When this transformation is applied on the provided XML document:

<Orders>     <Order>         <OrderId>O1</OrderId>         <SupplierId>S1</SupplierId>     </Order>     <Order>         <OrderId>O2</OrderId>         <SupplierId>S1</SupplierId>     </Order>     <Order>         <OrderId>O3</OrderId>         <SupplierId>S2</SupplierId>     </Order>     <Order>         <OrderId>O4</OrderId>         <SupplierId>S2</SupplierId>     </Order>     <Order>         <OrderId>O5</OrderId>         <SupplierId>S2</SupplierId>     </Order> </Orders> 

the desired result is produced:

  First OrderId = O1    Changes in Order OrderId = O3      SupplierId = S2   Previous Order OrderId = O2              SupplierId = S1    Last OrderId = O5