Re: [xsl] grouping references so that they only appear once

["G. Ken Holman" <gkholman@xxxxxxxxxxxxxxxxxxxx>]

At 2003-05-28 16:01 -0700, Rick Geimer wrote:
> I have a grouping problem that I am hoping someone can help me with.
> Imagine that I am transforming the following instance, and that I am
> currently processing the category element with  the id "shoes".
> ...
>       <makers>
>             <maker id="nike">Nike</maker>
>             <maker id="rebok">Rebok</maker>
>       </makers>
> ...
>       <products>
>             <product>
> ...
>                   <makerRef idref="nike"/>
>             </product>
>             <product>
> ...
>                   <makerRef idref="nike"/>
>             </product>
>             <product>
> ...
>                   <makerRef idref="rebok"/>
> ...
> I want to get a list of all the makers that have products that reference
> the shoes category, but I don't want a single maker to appear more than
> once. I have been able to use keys to gather a list of products that
> reference a category, and from there I can get the makerRefs, and with
> another set of keys I can then get the makers, but I can't see how to
> ensure that each maker is only listed once since multiple products
> reference the same makers.

It is unclear to me why you are getting duplicate <maker> elements from 
your key() access using the <makerRef> ... because in XPath 1.0 the node 
set returned from your use of key() won't have duplicate nodes.

I agree that if you try to process the <makerRef> nodes, you will have 
duplicates ... but you said you are using "another set of keys" to get the 
<makers>.  Assuming you have a variable of the <makerRef> elements, the 
function key( 'makersById', $makerRefs/@idref ) would only return 2 nodes, 
not three, because the three reference address only two unique nodes.

You'll have to show how your code is producing multiple <maker> elements 
since your prose description wouldn't appear to support the evidence.

I hope this helps.

....................... Ken

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G. Ken Holman                mailto:gkholman@xxxxxxxxxxxxxxxxxxxx
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