RE: [xsl] Use of xsl:key to perform node traversal according to an assoc

Hey Mike.

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Has anyone got any clues about what is wrong with?
<xsl:key name="player-id" match="Teams_and_Players/Players/Player"
use="@id"/>
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Nothing wrong here - you're pointing at the
Teams_and_Players/Players/Player nodes, saying "Whenever I feed this key
a value that matches the value of this node's @id, return this node."
That's all good.


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<xsl:value-of select="key('player-id', @id)"/>
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Here's the problem - this call to the key 'player-id' is passing
nothing, because it's in the TeamPlayer template, and TeamPlayer doesn't
have an id attribute! You want this:

<xsl:value-of select="key('player-id', .)"/>

That'll pass the value of the current node (TeamPlayer, in this case,
whose value is its text content) into the key, where it'll match against
the @id value in the //Teams_and_Players/Players/Player nodes.


Hope that helps! Make sure you spend a few minutes reviewing the
definition of <xsl:key/> and key(), and know exactly how and why they
work; the performance boost you'll get in any complicated stylesheet
will be well worth it.

~ Scott





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-----Original Message-----
From: Dunk, Michael (Mike) [mailto:mikedunk(_at_)fairisaac(_dot_)com] 
Sent: Wednesday, September 26, 2007 9:15 AM
To: xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com
Subject: [xsl] Use of xsl:key to perform node traversal according to an
association between nodes

Thank you to Michael Kay and Wendell Piez for their help with processing
context and paths. 

George Cristian Bina your comments about namespaces were appreciated.

I am struggling to find any clues in the examples of xsl:key in the text
xslt books about to use xsl:key to retrieve the contents of an element.
Or as Wendell Piez described it "the use of a key to perform node
traversal according to an association between nodes". Here is an
simplified example of the type of xml input I need to read:

<?xml version="1.0" encoding="UTF-8"?>
<Teams_and_Players> 
  <Teams>
    <Team name="Man Utd">
 
<TeamPlayer>{0EA17FA0-D21B-4F1E-8B11-A250A6CF266C}+00000000</TeamPlayer>
 
<TeamPlayer>{1F3E974C-F180-45EB-AB59-4D1ACF4BB855}+00000000</TeamPlayer>
 
<TeamPlayer>{3F9BEEE0-35DB-4835-A89E-F2B240EC2CB0}+00000000</TeamPlayer>
    </Team>
  </Teams>
  <Players>
    <Player id="{0EA17FA0-D21B-4F1E-8B11-A250A6CF266C}+00000000"
name="Gary Neville"></Player>
    <Player id="{1F3E974C-F180-45EB-AB59-4D1ACF4BB855}+00000000"
name="Louis Saha"></Player>
    <Player id="{3F9BEEE0-35DB-4835-A89E-F2B240EC2CB0}+00000000"
name="Ryan Giggs"></Player>
  </Players>
</Teams_and_Players>


The xslt written to list the teams and players is :

<?xml version='1.0'?>
<xsl:stylesheet version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>
<xsl:output method="xml"/>

<xsl:key name="player-id" match="Teams_and_Players/Players/Player"
use="@id"/>

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

<xsl:template match="Teams_and_Players">
 <Teams>
  <xsl:apply-templates select="Teams"/>
 </Teams>       
</xsl:template>

<xsl:template match="Teams">
  <xsl:apply-templates select="Team"/>
</xsl:template>

<xsl:template match="Team">
  <Team>
  <xsl:value-of select="@name"/>
  <xsl:apply-templates select="TeamPlayer"/>
  </Team>
</xsl:template>

<xsl:template match="TeamPlayer">
  <Player>
  <xsl:value-of select="key('player-id', @id)"/>
  </Player>
</xsl:template>
</xsl:stylesheet>

Currently the following is output:

<?xml version="1.0" encoding="UTF-8"?>
<Teams>
  <Team>Man Utd
    <Player/>
    <Player/>
    <Player/>
  </Team>
</Teams>


or

<xsl:value-of select="key('player-id', @id)"/>

Best regards,

Mike


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