Question

I want to have a key value map in xsl and so defined a variable which has an xml fragment, but later when I try to access the xml nodes in the variable I get an error that type of the xpath xpression cannot be resolved.

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:template match="/">
        <xsl:variable name="map">
            <map>
                <entry key="key-1">value1</entry>
                <entry key="key-2">value2</entry>
                <entry key="key-3">value3</entry>
            </map>
        </xsl:variable>
        <output>
            <xsl:value-of select="$map/entry[@key='key-1']"/>
        </output>
    </xsl:template>
</xsl:stylesheet>

Answer 1

XSLT 2.0

Using XSLT 2.0, the following solution works:

  <xsl:variable name="map">
    <entry key="key-1">value1</entry>
    <entry key="key-2">value2</entry>
    <entry key="key-3">value3</entry>
  </xsl:variable>

  <xsl:template match="/">
    <output>
      <xsl:value-of select="$map/entry[@key='key-1']"/>
    </output>
  </xsl:template>

XSLT 1.0

You cannot use a result tree fragment in a XPath expression in XSLT 1.0, but fn:document() can retrieve map values. An answer to a similar question will work here:.

<xsl:value-of select="document('')//xsl:variable[@name='map']/map/entry[@key='key-1']"/>

As described in the XSLT 1.0 specification:

document('') refers to the root node of
the stylesheet; the tree
representation of the stylesheet is
exactly the same as if the XML
document containing the stylesheet was
the initial source document.

However, you don’t need to use xsl:variable for this. You could specify your map node directly under xsl:stylesheet, but you must remember that a top level elements must have a non null namespace URI:

<xsl:stylesheet 
  version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
  xmlns:my="some.uri" exclude-result-prefixes="my">

  <my:map>
    <entry key="key-1">value1</entry>
    <entry key="key-2">value2</entry>
    <entry key="key-3">value3</entry>
  </my:map>

  <xsl:template match="/">
    <output>
      <xsl:value-of select="document('')/*/my:map/entry[@key='key-1']"/>
    </output>
  </xsl:template>
</xsl:stylesheet>