Re: AW: AW: Using key() from outside the default names

Peter Flynn wrote:
>On Wed, 2003-08-06 at 16:07, Markus Abt wrote:
>> I can see the problem. However, the reason for the root template to
>> be instantiated more than once is not the global variable $maindoc
>> that holds the root node of the main document, nor is it the dummy
>> <xsl:for-each> to switch the context back to the main document.
>
>OK.
>
>> The reason is:
>> 
>> (1) In your entry template, you define the variable $content with:
>>         <xsl:variable name="content">
>>           <xsl:for-each select="$maindoc">
>>             <xsl:value-of select="key($keyname,$entryid)"/>
>>           </xsl:for-each>
>>         </xsl:variable>
>> The value of this variable is now a result tree fragment, containing a
>> root node and a text node with the string from the <xsl:value-of>.
>
>So this for-each applied to my $maindoc actually places a node into the
>variable? Yuck.

(??) No, the variable $maindoc remains unchanged. The variable $contents
is set, but not from the for-each, it is set from the result of value-of.

The for-each is looping exactly one time, since $maindoc contains
exactly one node (the root node /).

>Oddly, if I declare maindoc to be some empty unused element buried deep
>in the document (*anything* which will get me back to the main doc), it
>still triggers the root template.

Nothing is "triggered" here. 

Again, the for-each is looping exactly one time, since $maindoc contains
one node (the empty node you chose).

Honest, the "trigger problem" is not here, but in (2) below.

>> (2) In your format template, you use this variable (via the param of
>> the same name):
>>         <xsl:apply-templates select="$content"/>
>
>Right, because $content may contain further subelements which need
>matching in templates.

No, it does only contain one root node and one text node, since the
value-of doesn't return the whole tree but only the first text node.

If you use copy-of instead of value-of, then the variable $content will
contain a result tree fragment with all subelements.

>> This results in applying ("firing" in your words):
>> -  The root template, and then
>> -  the default template for text nodes.
>> 
>> So you get the output from the root template more than once.
>
>Thank you very much, this explains what's happening. I really hadn't
>expected the for-each to insert anything into the variable.

See above, the for-each does *not* do that.

>What I need is a key-with-respect-to-where-I-tell-it($foo,$bar).
>
>> One solution would be to replace the <xsl:apply-templates>
>> with a <xsl:value-of> to output only the text node of this
>> result tree fragment:
>>         <xsl:value-of select="$content"/>
>
>Unfortunately not. The possibility of subelements needing processing
>within $content precludes this.

If you use copy-of instead of value-of to construct the value of
the variable, as I wrote above, then and only then $content will
contain the subelements.

Then, you can either
-  use <xsl:copy-of select="$content"/> here to copy the result
   tree fragment to the output *without processing*, or
-  use <xsl:apply-templates select="xx:node-set($content)/node()"/>
   to first convert the result tree fragment to a node set, and then
   apply templates to the resulting node-set.
   Note the .../node() here, to avoid "firing" of the root template...

xx:node-set() is an extension function that must be supported by
your xslt processor. Major processors have such an extension
function. Look into the their docu, or start reading at:
http://www.exslt.org/exsl/functions/node-set/index.html

>It looks as if it simply isn't possible in XSLT transparently to
>revisit a document like this to retrieve a key value. 

No, it is, via a node-set() extension function.

>///Peter

Regards,
Markus
__________________________
Markus Abt
Comet Computer GmbH
http://www.comet.de



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