Question

I’m trying to retrieve the attribute value from an xsl:param and use it in an xsl:if test condition.
So given the following xml

<product>
  <title>The Maze / Jane Evans</title> 
</product>

and the xsl

<xsl:stylesheet version="1.0"
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:output omit-xml-declaration="yes" indent="yes"/>
    <xsl:strip-space elements="*"/>

<xsl:param name="test" select="Jane"/>

 <xsl:template match="title[contains(., (REFERENCE THE SELECT ATTRIBUTE IN PARAM))]">
   <h2>
    <xsl:value-of select="substring-before(., '/')"/>
   </h2>
   <p>
    <xsl:value-of select="substring-after(., '/')"/>
   </p>
 </xsl:template>

 <xsl:template match="title">
   <h2><xsl:value-of select="."/></h2>
 </xsl:template>
</xsl:stylesheet>

I would like to get back

The Maze

Jane Evans

Answer 1

You have a problem in this line:

<xsl:param name="test" select="Jane"/>

This defines an xsl:param named test, whose value is the child element of the current node (‘/’) named Jane. As the top element is <product> and not <Jane>, the test parameter has the value of an empty node-set (and a string value — the empty string).

You want (notice the surrounding apostrophes):

<xsl:param name="test" select="'Jane'"/>

The whole processing task can be implemented rather easily:

This XSLT 1.0 transformation:

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>
 <xsl:strip-space elements="*"/>

 <xsl:param name="pTest" select="'Jane'"/>

 <xsl:template match="title">
  <xsl:choose>
    <xsl:when test="contains(., $pTest)">
       <h2>
        <xsl:value-of select="substring-before(., '/')"/>
       </h2>
       <p>
        <xsl:value-of select="substring-after(., '/')"/>
       </p>
    </xsl:when>
    <xsl:otherwise>
      <h2><xsl:value-of select="."/></h2>
    </xsl:otherwise>
  </xsl:choose>
 </xsl:template>
</xsl:stylesheet>

when applied on the provided XML document:

<product>
    <title>The Maze / Jane Evans</title>
</product>

produces the wanted, correct result:

<h2>The Maze </h2>
<p> Jane Evans</p>

Explanation:

The XSLT 1.0 syntax forbids variable/parameter references in a match pattern. This is why we have a single template matching any title and we specify inside the template the conditions for processing in a specific, wanted way.

An XSLT 2.0 solution:

<xsl:stylesheet version="2.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>
 <xsl:strip-space elements="*"/>

 <xsl:param name="pTest" select="'Jane'"/>

 <xsl:template match="title[contains(., $pTest)]">
   <h2>
     <xsl:value-of select="substring-before(., '/')"/>
   </h2>
   <p>
     <xsl:value-of select="substring-after(., '/')"/>
   </p>
 </xsl:template>

 <xsl:template match="title">
   <h2><xsl:value-of select="."/></h2>
 </xsl:template>
</xsl:stylesheet>

When this transformation is applied on the provided XML document (above), again the same wanted, correct result is produced:

<h2>The Maze </h2>
<p> Jane Evans</p>

Explanation:

XSLT 2.0 doesn’t have the limitations of XSLT 1.0 and variable/parameter references can be used within a match pattern.