同一父类的子类的Scala类型不匹配

Question

UserGetResponse and GeneralResponse are sublclasses of BaseResponse, which is as follows:

abstract class BaseResponse()

And the function I use to retrieve users is as follows:

  def userGet(userId: Int)(implicit ec: ExecutionContext): Future[BaseResponse] = Future {
    val response = users.get(userId) map { user =>
        val userRes = new UserResponse(user.id, user.firstname, user.lastname, user.organisationid, user.email, user.password, user.usertype)
        new UserGetResponse(1, "Successful retrieved the user.", userRes)
    } getOrElse {
      GeneralResponse(0, s"Error retrieving user. User does not exist.")
    }
  }

where users is another class with methods get, insert etc. defined. I am getting the following compilation error:

 type mismatch;
[error]  found   : Unit
[error]  required: package.name.BaseResponse
[error]   }

What am I doing wrong?

Answer 1

The closure inside the Future is not returning anything, so the compiler infers that it's return type is Unit , and complains because it should be BaseResponse .

Removing val response = from the beginning of the function (or adding response before the end) should fix it.