I am trying to create an index based on 3 elements but not sure if it is possible.

the following is sample lookup xml document and i need to retrieve <target_value> given <stream>, <codetype> and <source_sourcevalue>.

<lookups>
      <lookup>
            <stream>client</stream>
            <codetype>entity.title_id</codetype>
            <source_sourcesystem>XXX</source_sourcesystem>
            <source_sourcetable>entity</source_sourcetable>
            <source_sourcefielddescription/>
            <source_sourcevalue>92</source_sourcevalue>
            <target_description>-</target_description>
            <target_codetype>Title</target_codetype>
            <target_value>20092<target_value</>
            <target_table>_client</target_table>
      </lookup>
      <lookup>
            <stream>client</stream>
            <codetype>entity.title_id</codetype>
            <source_sourcesystem>XXX</source_sourcesystem>
            <source_sourcetable>entity</source_sourcetable>
            <source_sourcefielddescription>Abbot</source_sourcefielddescription>
            <source_sourcevalue>62</source_sourcevalue>
            <target_description>-</target_description>
            <target_codetype>Title</target_codetype>
            <target_value>10062<target_value</>
            <target_table>_client</target_table>
      </lookup>
</lookups>

and the following is snapshot of my XSLT that does the lookup


<xsl:variable name="lookupDoc" select="document('lookup.xml')"/>

<xsl:key use="stream|codetype|source_sourceValue" name="getLookUp" match="lookup"/>

<xsl:template name="lookup">
      <xsl:param name="stream"/>
      <xsl:param name="codeType"/>
      <xsl:param name="sourceValue"/>



      <xsl:value-of select="string(key('getLookUp', concat(stream, codeType, sourceValue))/target_value)"/>
</xsl:template>


thanks

There's no built-in capability for multi-part keys in XSLT but you can do-it-yourself using string concatenation. Just make sure you use the same expression in the "use" attribute of xsl:key and in the second argument of the key function:

use = "concat(stream, '#', codeType, '#', sourceValue)"

key('k', concat(stream, '#', codeType, '#', sourceValue))

In 2.0 you can use a user-defined function to hide the sordid detail:

use="f:compound-key(stream, codeType, sourceValue)"

key('k', f:compound-key(stream, codeType, sourceValue))

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

Thank you for the quick reply.

I realised that my above example doesnt work still. I read in one of your very old posting in biglist.com that if your lookup file is a separate XML document and it is declared as <xsl:variable name="colorLookupDoc" select="document('lookup.xml')"/> in the XSLT, then the XSLT must use <xsl:for-each select="$colorLookupDoc"> in order to lookup the value.

But will this slow down performance? I was hoping that a simple statement like <xsl:value-of select="key('kk', $index)"/> would do the job. I am essentially doing a lookup on about 50% of the nodes in the primary XML document and if the <xsl:for-value> is used then wouldnt it be better to use a direct XPath expression?

For example, the following is the lookup xml

<color>
    <cid>c1</cid>
    <value>yellow</value>
</color>
<color>
    <cid>c2</cid>
    <value>black</value>
</color>

then wouldnt it be better that i use
<xsl:value-of select="$lookupDoc/color[cid = $index]"/>

or would xsl:key still add value in performance?

thanks. I hope my explanantion makes sense.

If it didn't work with the second form, then you were doing something wrong.

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference