Re: [xsl] Extract values from first occurrence of a node

[Wendell Piez <wapiez@xxxxxxxxxxxxxxxx>]

Matt,

Although this can be done without them, keys are very useful in XSLT for 
this kind of operation.

You'd declare a key to match <B> elements, with the string value you care 
about (your substring) as the key value:

<xsl:key name="B-by-string" match="B" use="substring(.,1,5)"/>

Then the XPath "key('B-by-string','12344')" will get you all <B> elements 
that have that key value, while "key('B-by-string','12344')[1]" will get 
you the first of these (in document order). You could of course use a 
variable as that second argument.

Part of getting your head around XSLT's non-proceduralness is in learning 
the various ways nodes can be selected, without having to run processes 
over the set (or find out what processes may have already been run -- in a 
side-effect free system this isn't appropriate, desirable or generally 
possible).

Cheers,
Wendell

 At 12:09 PM 7/16/2003, you wrote:
> I am trying to translate XML via XSL/XSLT need to specifically extract the 
> values from the first occurrence of a particular node and ignore the rest 
> of that same node.
>
> I was attempting to use preceding-sibling::nodeset/node to verify if the 
> match has already been made, but having little luck because I not only 
> need to match the node but match substrings of the node's value.
>
> Example XML:
>
> <A>
> <B>12345 ABCD</B>
> <B>12344 ABCD</B>
> <B>12333 EFGH</B>
> <B>12344 WXYZ</B>
> </A>
>
> What I need to do:
>
> Recognize the first <B> with 12344 (substring from 1 with length 5) and 
> extract ABCD (substring from 7 with length 4), but ignore all other <B>
>
> This is a very basic example, the XML I am working with is a bit more 
> complicated and it is being translated via XSL-FO for PDF generation.
>
> The biggest problem I am having with XSL/XSLT is detaching from my 
> procedural language experience!  From my experience, I am having success 
> in mapping singlular nodes but more difficulty when trying to accomplish 
> "decision logic" in a non-procedural manner.
>
> Any suggestions or recommended reads would be great.
>
> Thanks,
> Matt
>
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Wendell Piez                            mailto:wapiez@xxxxxxxxxxxxxxxx
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