XSLT - computing numeric values

[Romain Thuaudet]

Hello guys,

I am totally new to XSLT and I need to use it to compute interest flows from a XML document.

Here is the relevant part of the XML document:

<interestPaymentPeriod type="paymentPeriod"> <calculationPeriod type="calculationPeriod"> <notionalAmount type="decimal">10000</notionalAmount> </calculationPeriod> <coupon type="decimal">1.71784</coupon> </interestPaymentPeriod> <interestPaymentPeriod type="paymentPeriod"> <calculationPeriod type="calculationPeriod"> <notionalAmount type="decimal">10000</notionalAmount> </calculationPeriod> <coupon type="decimal">1.86914</coupon> </interestPaymentPeriod> <interestPaymentPeriod type="paymentPeriod"> <calculationPeriod type="calculationPeriod"> <notionalAmount type="decimal">10000</notionalAmount> </calculationPeriod> <coupon type="decimal">1.79553</coupon> </interestPaymentPeriod>
What I want to do is to get the sum of the quantities notionalAmount*coupon present in each interestPaymentPeriod node. For instance here, the result expected would be 1.71784*10000+1.86914*10000+1.79553*10000= 53825.1

The tricky part is that I don't know how many interestPaymentPeriod nodes I am going to have. There can be 1 node or 22 of them.
So far I tried to do this with a for-each loop and I have also tried to emulate a while loop with no success.
Here is my XSLT formula with the for-each loop:
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:template match="/"> <xsl:variable name="coupon" select="number(0)"/> <xsl:variable name="nominal" select="number(0)"/> <xsl:variable name="margin.flow" select="number(0)"/> <xsl:variable name="interest.flows" select="number(0)"/> <xsl:for-each select="/trades/trade/interestFlows/interestPaymentPeriod"> <xsl:variable name="coupon" select="coupon"/> <xsl:variable name="nominal" select="calculationPeriod/notionalAmount"/> <xsl:variable name="margin.flow" select="$coupon * $nominal"/> <xsl:variable name="interest.flows" select="$interest.flows + $margin.flow"/> </xsl:for-each> <xsl:value-of select="$interest.flows"/> </xsl:template> </xsl:stylesheet> ]
It does not work, I dont retrieve any values. Could someone please take a look at it ? I am really new to XSLT, I am just an intern who has to take care of this and I am sorry if there are silly mistakes in my code.

Sorry for my potential english mistakes!

Thanks a lot for your help!

[Matthew Brown]

Hi Romain. Welcome to The Ranch!

"Variables" in XSLT are a bit misleadingly named. They aren't, really. Once assigned they can't be reassigned. Therefore, you can't use them in a procedural way like you're trying to do here.

My XSLT is very rusty, but I'd probably try a recursive method for this. Here's an example. Be warned, though, this is off the top of my head and hasn't been tested!
... <!-- This bit calls the recursive template, passing in all the payment periods --> <xsl:variable name="total"> <xsl:call-template name="calculate-interest"> <xsl:with-param name="interestPaymentPeriods" select="/trades/trade/interestFlows/interestPaymentPeriod"/> </xsl:call-template> </xsl:variable> ... <!-- And this named template does the calculations --> <xsl:template name="calculate-interest"> <xsl:param name="interestPaymentPeriods"/> <xsl:choose> <!-- If there are any remaining periods to calculate ... --> <xsl:when test="$interestPaymentPeriods"> <xsl:variable name="thisPeriod" select="$interestPaymentPeriods[0]"/> <!-- ...add the interest from the first period ... --> <xsl:variable name="currentValue" select="...single period calculation..."/> <!-- ...to the interest from all the rest ... --> <xsl:variable name="remainingValue"> <xsl:call-template> <xsl:with-param name="interestPaymentPeriods" select="$thisPeriod/following-sibling::interestPaymentPeriod"/> </xsl:call-template> </xsl:variable> <xsl:value-of select="$currentValue + $remainingValue"/> </xsl:when> <!-- If there aren't any periods, return zero --> <xsl:otherwise> <xsl:value-of select="number(0)"/> </xsl:otherwise> </xsl:choose> </xsl:template>