在 ActionBuilder 中从 Future 中提取选项

问题描述

我正在基于此 Scala Play Authentication 示例实施身份验证。

因此，我使用以下 ActionBuilder 来构建 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)
  }
}

由于 example implementation in line 25 不返回 Future 因为没有包含数据库设置，我收到以下错误：

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

因为我是 Scala 的新手，所以我现在不知道如何提取 Future。如何处理 Future 结果以确保我们返回 Option[Admin]？

解决方法

我自己修好了。我只是将电子邮件和提取分为两个不同的部分，并将 Future 移到 email match 内。

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) }
    }
  }
}