test attribute null evaluation doesn 't work 2003-05-06 - By david_marston@(protected)
>This code evaluates to true when StartTime is not set.
> <xsl:when test="$StartTime">
>I want it to evaluate to false. It worked fine in xalan-1.
And the variable was set by....
<xsl:variable name="StartTime">
<xsl:if test="...">
<xsl:value-of select="substring-before($TimeValues, ';')"/>
</xsl:if>
</xsl:variable>
This probably represents a required tightening-up between 1.x and 2.x.
As you've structured it, $StartTime contains a result tree fragment
(RTF), which you should read about in a good XSLT book. The RTF is
never totally empty.
Fortunately, your case has the easy workaround of just inverting the
structure:
<xsl:if test="...">
<xsl:variable name="StartTime" select="..."/>
</xsl:if>
For more complicated situations, you could have a flag value that is
outside the range of valid times, or you could have a second boolean
variable $StartTimeSet to use in the xsl:when.
.................David Marston
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