Rob Bowman

If you try and implement if then else logic in XSLT in the same way that you would in a procedural language then you'll probably end up tying yourself in knots.

 

I had some XSLT to write today where I simply needed to check the existance of an attribute in the source document. If it existed then I would execute and addition against the value else I would substitue for a zero.

 

I had initially approached this with something like:

 

<xsl:choose>

  <xsl:when test="referenceToElemen/@attribute">

    <xsl:variable name="x" select = "referenceToElemen/@attribute">

  </xsl:when>

  <xsl:otherwise>

     <xsl:variable name="x">0</xsl:variable>

  </xsl:otherwise>

<xsl:choose>

 

<resultElement>

  <xsl:value-of select = "$x + 100"

</eesultElement>

 

Unfortunately this will not work because the scope of the vairable x is confined to the choose block.

 

The solution is to kind of turn the XSL variable declaration inside out, as shown below:

 

   <xsl:variable name ="PriceDiscount">
    <xsl:choose>
     <xsl:when test ="oms:OrderHeader/oms:OrderSummary/@Total">
      <xsl:value-of select ="oms:OrderHeader/oms:OrderSummary/@Total"/> 
     </xsl:when>
     <xsl:otherwise>0</xsl:otherwise>
    </xsl:choose>
   </xsl:variable>

   <xsl:variable name ="StaffDiscount">
    <xsl:choose>
     <xsl:when test ="oms:OrderHeader/oms:OrderSummary/@StaffDiscount">
      <xsl:value-of select ="oms:OrderHeader/oms:OrderSummary/@StaffDiscount"/>
     </xsl:when>
     <xsl:otherwise>0</xsl:otherwise>
    </xsl:choose>
   </xsl:variable>

   <t3m:introduced_by>
    <xsl:value-of select = "$PriceDiscount + $StaffDiscount"/>
   </t3m:introduced_by>