XQuery that updates if something is true and otherwise returns error

Question

I'm trying to create a xquery expressions that inserts some new nodes only if a condition is true and returns an error if the condition is false. A simplyfied version of my state is:

let $a := [...]

return 
  if($a/@something != "true") then (
     insert node (
            element {'Foobar'} { }
        ) into $a/somenode
  ) else ( 

  )

My problem: whenever if put something like <Error/> into the else i get an error "[XUST0001] No updating expression allowed in this context".

/e: Okay...if I understand this correctly i can't have updateing expressions AND a return value....so I have to find another way.

Answer 1

You can use fn:error() to raise the error, or use () to do nothing. Unfortunately XQuery Update doesn't allow you to do what you want - maybe it will be fixed in a future version.