I'm trying to sum up a set of values in an XML using XSLT and XPath function fn:sum. This works fine as long as the values are non-null, however this is not the case. To illustrate my problem I've made an example:
<?xml version="1.0"?>
<xsl:stylesheet version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:fn="http://www.w3.org/2005/xpath-functions">
<xsl:template match="/root">
<root>
<!-- Works fine for non-null values -->
<sum><xsl:value-of select="fn:sum(values/value)" /></sum>
</root>
</xsl:template>
</xsl:stylesheet>
and the XML:
<?xml version="1.0"?>
<root>
<values>
<value>1</value>
<value>2</value>
<value>3</value>
<value>4</value>
<!-- Nullvalue -->
<value />
</values>
</root>
The example works fine as long as there's no null-values. I've tried various variants of the select, such as <xsl:value-of select="fn:sum(values[value != '']/value)" />
(as you might notice, not much of an XSLT export ;) ) How can I filter out the null-values?
Explicitly test that the nodes have content:
<sum><xsl:value-of select="fn:sum(values/value[text()])" /></sum>
I think that what you mentioned:
<xsl:value-of select="fn:sum(values[value != '']/value)" />
does not work, because the node is empty - it does not contain a text node at all, whereas value != ''
tests for an empty string - that is, a text node having data of length 0.
To sum just the elements that contain numbers:
<sum>
<xsl:value-of select="fn:sum(values/value[number(.)=number(.)])" />
</sum>
The result of number()
will be NaN
for empty elements, or elements whose string value is not a number.
MSDN reference - http://msdn.microsoft.com/en-us/library/ms256211.aspx
http://www.stylusstudio.com/xsllist/199909/post60110.html
<?xml version="1.0"?>
<doc>
<num>1</num>
<num>7</num>
<notnum>hello world</notnum>
<num>4</num>
</doc>
<?xml version="1.0"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/XSL/Transform/1.0">
<xsl:template match="/">
<xsl:value-of select="sum(/doc/num)"/>
</xsl:template>
</xsl:stylesheet>
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