Conditional variable set to RTF

Belch · October 17th, 2011, 09:56 AM

Hello all,

I am having an issue trying to set a conditional variable (which I know is tricky anyway in XSLT) to a path.

I am declaring the variable name first, and then within the xsl:variable tags I have the xsl:choose that checks a condition and outputs one of two possible paths - the aim being that I can then use the variable as a 'root' for all other paths in the stylesheet.

Below is the code for the variable:

Code:

<xsl:variable name="Root">
  <xsl:choose>
    <xsl:when test="somepath/sometag = 'abcd'">
      rootone/roottwo[@desc='firsttype']
    </xsl:when>
    <xsl:otherwise>
      rootone/roottwo[@desc='othertype']
    </xsl:otherwise>
  </xsl:choose>
</xsl:variable>

I have tried doing this with <xsl:text> tags around the paths, <xsl:value-of> and <xsl:copy-of> tags, but no joy.

With these I get the error:
org.apache.xpath.objects.XRTreeFrag cannot be cast to org.apache.xpath.objects.XNodeSet
if I try to use the variable within an XPath expression, for example:
$Root/name/surname/.

If the variable isn't conditional, e.g.:

Code:

<xsl:variable name="Root" select="rootone/roottwo[@desc='firsttype']" />

then it works fine.

I understand that a conditional variable will set the variable value to a RTF (result tree fragment) rather than a node-set, which is what I need to be able to use it within another path.
I had thought converting it to text would work as it would add it to the additional path and read it as a path.

Please could someone advise how else I can use this conditional variable?
I am using xslt 1.0, but couldn't see any node-set functions even in xslt 2.0.

Thanks in advance,

mhkay · October 17th, 2011, 10:15 AM

XPath expressions in XSLT always go in attributes, never in text nodes. And an RTF will never select excising nodes, it will always create new nodes.

You're presumably on XSLT 1.0 (this would be very easy in XSLT 2.0, and since you're writing in Java there's really no excuse not to move forward.)

You need something like this:

Code:

<xsl:variable name="condition" select="somepath/sometag = 'abcd'"/>
<xsl:variable name="Root" select="
    rootone/roottwo[@desc='firsttype'][$condition] |
    rootone/roottwo[@desc='othertype'][not($condition)]"/>

In 2.0 it would be simply:

Code:

<xsl:variable name="Root" select="
    rootone/roottwo[@desc=if ($condition) then 'firsttype' else 'other type']

Belch · October 17th, 2011, 10:58 AM

Hi Michael,

That solution works perfectly, and makes sense now I can see it written out!

Thanks very much for the quick reply.