[xsl] Re: Lookup in a xml file with a key

Subject: [xsl] Re: Lookup in a xml file with a key
From: Dimitre Novatchev <dnovatchev@xxxxxxxxx>
Date: Tue, 10 Jul 2001 03:48:59 -0700 (PDT)
Gaston Annebicque wrote:

> Hi,

> Here is my problem :
> I have this xml file :
> <in>
> 	<country>010</country>
> 	<country>020</country>
> </in>
> and with this other xml file that describe a table, I named the file
> "lookup.xml" :
> <?xml version="1.0"?>
> <lookup>
> 	<countrydef>
> 		<abbr>010</abbr>
> 		<name>Germany</name>
> 	</countrydef>
> 	<countrydef>
> 		<abbr>020</abbr>
> 		<name>France</name>
> 	</countrydef>
> </lookup>
> I would like to output the following :
> <out>
> Germany
> France
> </out>
> I can't manage to get my xslt to work, here is the current version of it :
> <xsl:stylesheet version="1.0"
> xmlns:xsl="http://www.w3.org/1999/XSL/Transform";;>
>   <xsl:output indent="yes" omit-xml-declaration="yes"/>
>   <xsl:key name="kLookup" match="abbr" use="name"/>
>   <xsl:template match="/">
>     <in>
>       <xsl:apply-templates select="in/country"/>
>     </in>
>   </xsl:template>
> <xsl:template match="in/country">
>     <xsl:variable name="input" select="."/>
>      <xsl:for-each select="document('c:/gaston/lookup.xml')">
>         <xsl:for-each select="key('kLookup',name($input))">
>             <xsl:value-of select="."/>
>         </xsl:for-each>
>      </xsl:for-each>
> </xsl:template>
> </xsl:stylesheet>
> If someone could help me with that, I'm totaly lost !!
> Thanks, Gaston.

Hi Gaston,

It is not enough to have working code -- one needs to understand it.

Why isn't your stylesheet producing the desired results?

1. You must understand how xsl:key and the key() function work. 
   in case you want to transform an abbreviation to "name" (which is exactly your 
   case), then the way you define the key:

>   <xsl:key name="kLookup" match="abbr" use="name"/>

   this performs exactly the opposite transformation. Also, you failed to notice 
   that in your lookup file "abbr" and "name" are not parent/child but just

   The correct definition of the key will be:

  <xsl:key name="kLookup" match="name" use="../abbr"/>

2. Using name($input) in
>         <xsl:for-each select="key('kLookup',name($input))">
   in a template matching "country" will always return "country" -- and of course
   this is not what you need. 

   The correct code will read:

   <xsl:for-each select="key('kLookup',$input)">

Putting all together, here's the stylesheet that will produced the required output
when applied on your xml source file:

<xsl:stylesheet version="1.0"
  <xsl:output indent="yes" omit-xml-declaration="yes"/>
  <xsl:key name="kLookup" match="name" use="../abbr"/>

  <xsl:template match="/">
      <xsl:apply-templates select="in/country"/>

<xsl:template match="country">
    <xsl:variable name="input" select="."/>
     <xsl:for-each select="document('lookup2.xml')">
        <xsl:for-each select="key('kLookup',$input)">
            <xsl:value-of select="."/>

Hope this helped.

Dimitre Novatchev.

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