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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