Serving rest requests: how to avoid code duplication

Question

In the rest part of my lift application I often have code like this:

object UserRest extends RestHelper {
    serve("user" :: Nil prefix {
        case Req("remove-item" :: itemId :: Nil, "json", PostRequest) => {
            User.currentUser.map{ u =>
              //doing some things and returning message
              "Ready, all right."
            }.getOrElse("You must be logged in to perform this operation.")
         }: JValue

        case Req("update-item" :: itemId :: Nil, "json", PostRequest) => {
            User.currentUser.map{ u =>
              //doing some things and returning message
              "Ready, all right."
            }.getOrElse("You must be logged in to perform this operation.")
         }: JValue
    }
}

As you can see for every user operation I have this piece of code:

User.currentUser.map{ u =>
    //...
}.getOrElse("You must be logged in to perform this operation.")

My question is - do I have a way to put this piece of code to one place to avoid repeating it for every request?

Answer 1

You could write a function to handle unboxing objects for you. Something like this should help:

def unbox[A](t:Box[A])(a: A => JValue) = { 
  val msg = "You must be logged in to perform this operation."
  t.map { u => a(u) }.getOrElse(JString(msg)) 
}

Then, you'd just call it like :

unbox(User.current){ u:User => 
   //doing something
   JString("Ready, all right.")
}