Play 2.2 EssentialAction With Futures

问题:

I'm trying to implement an authentication mechanism similar to this example:

    def HasToken(action: String => EssentialAction): EssentialAction = EssentialAction { requestHeader =>
      val maybeToken = requestHeader.headers.get("X-SECRET-TOKEN")
      maybeToken map { token =>
        action(token)(requestHeader) // apply requestHeader to EssentialAction produces the Iteratee[Array[Byte], SimpleResult]
      } getOrElse {
        Done(Unauthorized("401 No Security Token\n")) // 'Done' means the Iteratee has completed its computations
      }
    }

However, in my case I'm mapping a random token value to a session on the server side stored in Mongodb. The goal was to be able to let a user terminate all his other sessions at will.

However, the data I get from ReactiveMongo is going to be wrapped in a Future.

I would like something like this:

    def HasToken(action: String => EssentialAction): EssentialAction = EssentialAction { requestHeader =>
      val maybeToken = requestHeader.headers.get("session")
      maybeToken map { token =>
        //This returns a future..
        Session.find(session).map { result => 
          result match
            case Some(session) => action(session)(requestHeader)
            case None => Done(Unauthorized())
        }
      } getOrElse {
        Done(Unauthorized("401 No Security Token\n")) // 'Done' means the Iteratee has completed its computations
      }
    }

Is this possible with EssentialAction?

回答1:

Iteratee.flatten goes from Future[Iteratee[A, E]] => Iteratee[A, E] so you could do it like this:

def HasToken(action: String => EssentialAction): EssentialAction = EssentialAction { requestHeader =>
   val maybeToken = requestHeader.headers.get("session")

   val futureIteratee: Future[Iteratee[Array[Byte], SimpleResult]] = maybeToken map { token =>
     //This returns a future..
     Session.find(token).map {
       case Some(session) => action(session)(requestHeader)
       case None => Done[Array[Byte], SimpleResult](Unauthorized("Invalid token"))
     }
   } getOrElse {
     Future.successful(Done[Array[Byte], SimpleResult](Unauthorized("401 No Security Token\n")))
   }

   Iteratee.flatten(futureIteratee)
}

回答2:

You can use an ActionBuilder as the invokeBlock method return a Future[SimpleResult] so you can flatMap your future into a call to the underlying block

Something like

object Authenticated extends ActionBuilder[AuthenticatedRequest] {
  def invokeBlock[A](request: Request[A], block: (AuthenticatedRequest[A]) => Future[SimpleResult]) = {
    Session.find(session).map { result => 
      result match
        case Some(session) => block(new AuthenticatedRequest(session))
        case None => Unauthorized()
    }        
}

}

where AuthenticatedRequest is your request type that wraps your session object