scala - Scala / Play 2.5：重载方法适用于替代方案

Question

我正在使用 Scala & Play 2.5。我被这个错误困住了：

Game.scala:99: overloaded method value apply with alternatives:
[error]   (block: => play.api.mvc.Result)play.api.mvc.Action[play.api.mvc.AnyContent] <and>
[error]   (block: play.api.mvc.Request[play.api.mvc.AnyContent] => play.api.mvc.Result)play.api.mvc.Action[play.api.mvc.AnyContent] <and>
[error]   [A](bodyParser: play.api.mvc.BodyParser[A])(block: play.api.mvc.Request[A] => play.api.mvc.Result)play.api.mvc.Action[A]
[error]  cannot be applied to (Object)
[error]     def start(id: String, apiKey: Option[String]) = Action {

这是功能：

def start(id: String, apiKey: Option[String]) = Action {
  apiKey match {
    case Some(API_KEY) => {
      Server.actor ! Server.Start(id)
      Ok("Started")
    }
    case _ => Future.successful(Unauthorized)
  }
}

Answer 1

问题是，该match语句的结果已被推断为Object，因为从一个 case 语句中您正在返回Result，而从另一个 case 语句中您正在返回Future[Result]，所以唯一常见的超类型是Object. 要修复，请更改case _ => Future.successful(Unauthorized)为case _ => Unauthorized.