[MarkLogic Dev General] order modifier

[Shannon Scott Shiflett]

Mike,

Your response is extremely useful -- thank the gods for multiple  
OrderSpec expressions!

Regards,
Shannon

On May 21, 2008, at 3:22 PM, Michael Blakeley wrote:

> This is one of the uglier warts in XQuery. http://www.w3.org/TR/xquery/#id-flwor-expressions 
>  and http://www.w3.org/TR/xquery/#prod-xquery-OrderModifier specify  
> that OrderModifier is a literal token, not a variable or an  
> expression. So it's tricky to write dynamic sorts.
>
> But here is one approach, taking advantage of multiple OrderSpec  
> expressions:
>
> let $ascending := false()
> for $i in 1 to 10
> order by
>  if ($ascending) then $i else () ascending,
>  if ($ascending) then () else $i descending
> return $i
> =>
> 10 9 8 7 6 5 4 3 2 1
>
> Another technique is to build a query with the desired sorting, then  
> xdmp:eval() it. That's a very flexible approach, but somewhat error- 
> prone. If you go down that road, be sure to use external variables  
> to guard against escaping problems and query injections.
>
> -- Mike
>
> Shannon Scott Shiflett wrote:
>> hello,
>> is it possible in xquery flwor to use a conditional expression as  
>> the  order modifier of the order by clause?  i would like to  
>> specify  "ascending" or "descending" dynamically.
>> thanks,
>> shannon
>> _______________________________________________
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>> General at developer.marklogic.com
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>
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