当Option无时，Return Future失败

如何解决当Option无时，Return Future失败

我有下面的代码可以正常工作

case class MainRequest(optionalVal: Option[String])

case class IntermediateResult(someVal: String)

case class FinalResult(param: String)

def process(param: String,intermediateResult: IntermediateResult): Option[String] = ???

def getFutureOfList: Future[List[Int]] = ???

def getFutureOfOption(param: Int): Future[Option[IntermediateResult]] = ???

def overallResult(mainReq: MainRequest): Future[Option[FinalResult]] = {
  (for {
    optionalOne <- OptionT(getFutureOfList.map(_.headOption))
    optionalTwo <- OptionT(getFutureOfOption(optionalOne))
  } yield {
    mainReq.optionalVal.flatMap(process(_,optionalTwo)).map(FinalResult)
  }).value.map(_.flatten)
}

但是，现在，我需要更改overallResult函数，以便当mainReq.optionalVal为None或process(_,optionalTwo)产生None时，它将返回Future fail Exception。尽可能不更改函数的返回类型。

我在下面尝试过，但将来不能在yield内部失败。

def overallResult(mainReq: MainRequest): Future[Option[FinalResult]] = {
  (for {
    optionalOne <- OptionT(getFutureOfList.map(_.headOption))
    optionalTwo <- OptionT(getFutureOfOption(optionalOne))
  } yield {
    mainReq.optionalVal match {
      case Some(contains) =>
        process(contains,optionalTwo) match {
          case Some(result) => FinalResult(result)
          case None => new RuntimeException("process(contains,optionalTwo) resulted in None")
        }
      case None => new RuntimeException("mainReq.optionalVal resulted in None")
    }}).value.map(_.flatten)