scala – 使用Slick重构期间类型不匹配

def createAdmin(/* ... */): Future[Int] =
  db.run {
    {
      (users returning users.map(_.id)) += Account(0,/* ... */)
    } flatMap { id =>
      admins += Admin(userId = id,/* ... */)
    }
  }

def createStandardUser(/* ... */): Future[Int] =
  db.run {
    {
      (users returning users.map(_.id)) += Account(0,/* ... */)
    } flatMap { id =>
      standardUsers += StandardUser(userId = id,/* ... */)
    }
  }

编译好.但如果我将两者合并到以下内容中：

def createUser(role: String)(/* ... */): Future[Int] =
  db.run {
    {
      (users returning users.map(_.id)) += Account(0,/* ... */)
    } flatMap { id =>
      role match {
        case "admin" =>
          admins += Admin(userId = id,/* ... */)
        case "standard" =>
          standardUsers += StandardUser(userId = id,/* ... */)
      }
    }
  }

我收到以下类型不匹配错误：

[error]  found   : Long => slick.dbio.DBIOAction[Int,slick.dbio.NoStream,Nothing]
[error]  required: Long => slick.dbio.DBIOAction[Int,E2]
[error]       } flatMap { id =>
[error]                      ^
[error] one error found

我似乎无法弄清楚为什么.有人可以为我照亮这个吗？