Extract Option from Future in ActionBuilder

Question

I am implementing authentication based on this Scala Play Authentication example.

Therefore I use the following ActionBuilder to build an UserAction.

UserAction.scala

class UserRequest[A](val user: Option[Admin], request: Request[A]) extends WrappedRequest[A](request)

class UserAction @Inject()(adminService: AdminService, parser: BodyParsers.Default)(implicit val executionContext: ExecutionContext)
  extends ActionBuilder[UserRequest, AnyContent]
    with ActionTransformer[Request, UserRequest] {

  def transform[A](request: Request[A]) = Future.successful {

    val sessionTokenOpt = request.session.get("sessionToken")

    val user = sessionTokenOpt
      .flatMap(token => Sessions.getSession(token))
      .filter(_.expiration.isAfter(LocalDateTime.now(ZoneOffset.UTC)))
      .map(_.email)
       // Signature: getAdminByEmail(email: String): Future[Option[Admin]]
      .flatMap(adminService.getAdminByEmail) // <- Extract Future here

    // The user has to be Option[Admin] but is Future[Option[Admin]]
    // because of adminService.getAdminByEmail
    new UserRequest(user, request)
  }
}

Since the example implementation in line 25 does not return a Future because there is no database setup included, I get the following error:

type mismatch;
 found   : scala.concurrent.Future[Option[models.Tables.Admin]]
 required: Option[?]

Because I am new to scala I have no clue how to extract the Future at this point. How to handle the Future result to make sure we return a Option[Admin]?

Answer 1

Fixed it on my own. I just divided the email and fetching into two different parts and moved the Future inside the email match.

class UserAction @Inject()(adminService: AdminService, val parser: BodyParsers.Default)(implicit val executionContext: ExecutionContext)
  extends ActionBuilder[UserRequest, AnyContent]
    with ActionTransformer[Request, UserRequest] {

  def transform[A](request: Request[A]) : Future[UserRequest[A]] = {
    val sessionTokenOpt = request.session.get("sessionToken")

    val email = sessionTokenOpt
      .flatMap(token => Sessions.getSession(token))
      .filter(_.expiration.isAfter(LocalDateTime.now(ZoneOffset.UTC)))
      .map(_.email)

    email match {
      case Some(value) =>
        adminService.getAdminByEmail(value).map(a => new UserRequest(a, request))
      case None =>
        Future { new UserRequest(None, request) }
    }
  }
}