XSLT sum of values based on data in two different tables - xslt

Question

XML:
<Budget>
<Table1>
<AllocID>1</AllocID>
<Amount>1000</Amount>
</Table1>
<Table1>
<AllocID>2</AllocID>
<Amount>2000</Amount>
</Table1>
<Table1>
<AllocID>3</AllocID>
<Amount>3000</Amount>
</Table1>
<Table2>
<AllocID>1</AllocID>
<Split>100</Split>
</Table2>
<Table2>
<AllocID>2</AllocID>
<Split>100</Split>
</Table2>
</Budget>
I am displaying the amounts in a table, but only if a "Split" value exists in Table2.
<xsl:for-each select="Budget/Table1">
<xsl:for-each select="//Budget/Table2[AllocID = current()/AllocID]">
<xsl:value-of select="Amount"/>
</xsl:for-each>
</xsl:for-each>
//Total for the records here.
I need to get the sum of Amounts from Table1, but only if a value for the AllocID exists in Table2. So in this example, I only want the sum of Amount for AllocIDs 1 & 2. How would I do this in xslt without modifying the given datasets?

Answer 1

Knowing nothing else about your input data (I have no idea why you chose not to use actual XML), I'm going to have to to guess a little:
<Budget>
<Table1>
<AllocID>1000</AllocID>
<AllocID>2000</AllocID>
<AllocID>3000</AllocID>
</Table1>
<Table2>
<AllocID>1000</AllocID>
<AllocID>2000</AllocID>
</Table2>
</Budget>
Easiest is the XPath sum() function along with the right XPath expression:
<!-- this will return 3000 for the above input -->
<xsl:template match="/" >
<xsl:value-of select="
sum(Budget/Table1/AllocID[. = //Budget/Table2/AllocID])
" />
</xsl:template>
Running sums can also be calculated with a recursive function, like this:
<!-- this will also return 3000 for the above input -->
<xsl:template match="/" >
<xsl:call-template name="total">
<xsl:with-param name="nodes" select="
Budget/Table1/AllocID[. = //Budget/Table2/AllocID]
" />
</xsl:call-template>
</xsl:template>
<xsl:template name="total">
<xsl:param name="nodes" />
<xsl:choose>
<!-- either there is something to calculate... -->
<xsl:when test="string(number($nodes[1])) != 'NaN'">
<xsl:variable name="subtotal">
<xsl:call-template name="total">
<xsl:with-param name="nodes" select="$nodes[position() > 1]" />
</xsl:call-template>
</xsl:variable>
<xsl:value-of select="number($nodes[1]) + $subtotal" />
</xsl:when>
<!-- ...or we assume 0 -->
<xsl:otherwise>
<xsl:value-of select="0" />
</xsl:otherwise>
</xsl:choose>
</xsl:template>
This is slower, but allows for greater flexibility in the calculation process. You can replace all the non-numeric values with 0, for example. Or use different values of the given nodes according to your own rules.