Getting a list Of Authors for a User through liftweb's REST interface

gistfile1.txt

Given the  Following Mapper Data Model: 

Author <- 1) -> Book <- 2) -> User

1) An Author can have more books while books can be written by multiple authors (N-N)
2) A user can own multiple books, while a book can have multiple owners  (N-N)

note: When successfully authenticating in a user his API key is returned which is used in all other requests 

gistfile2.scala

serve {
  case "api" :: key :: "user" :: "authors" :: "all" :: _ XmlGet _ => {
    <Authors> {
      Book.findAll(In(Book.id ,BookUser.book, By(BookUser.user, getUserIdFromKey(key))))
        .map(book => { book.authors.get })
        .foldLeft(List[Author]())(_ ++ _)
        .distinct
        .map(author => author.toXml)
      }
    </Authors>
  }
  case "api" :: key :: "user" :: "authors" :: "all" :: _ JsonGet _ => {
    JsonWrapper ("Authors", {
      Book.findAll(In(Book.id ,BookUser.book, By(BookUser.user, getUserIdFromKey(key))))
        .map(book => { book.authors.get })
        .foldLeft(List[Author]())(_ ++ _)
        .distinct
        .map(author => author.toJson)
      })
  }
}

//helper methods

def getUserIdFromKey(key:String):Long = {
  User.find(By(User.key, key) match {
    case Full(user) => user.id
    case (_) => 0
  }
}

def JsonWrapper(name:String, value:JValue):JValue {
  (name, value)
}