Using fn:sum in XSLT with node-set containing null-values
xml, xpath, xslt
Solution
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.
Problem
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?