AlamofireObjectMapper返回nils

Question

我尝试使用AlamofireObjectMapper

映射以下JSON

{
  "res": [
    {
      "electiveClusterId": 25,
      "multipleSelectionEnabled": false,
      "electiveClusterName": null,
      "coursesList": [
        {
          "courseId": 6,
          "courseName": "Accounts",
          "selected": false,
          "classStarted": false
        },
        {
          "courseId": 19,
          "courseName": "Javascript",
          "selected": false,
          "classStarted": false
        }
      ]
    },
    {
      "electiveClusterId": 26,
      "multipleSelectionEnabled": true,
      "electiveClusterName": null,
      "coursesList": [
        {
          "courseId": 11,
          "courseName": "Algorithms and Logics",
          "selected": false,
          "classStarted": false
        },
        {
          "courseId": 15,
          "courseName": "Android App",
          "selected": false,
          "classStarted": false
        }
      ]
    }
  ]
}

以下是我各自的对象类：

    class ElectivesMainResponse: Mappable {

        private var _res: [ElectivesResponse]?

        var Res: [ElectivesResponse]? {
            return _res
        }

        required init?(map: Map){
            mapping(map: map)
        }

        func mapping(map: Map) {
            _res <- map["res"]
        }
    }

class ElectivesResponse: Mappable {
    private var _electiveClusterId: Int!
    private var _multipleSelectionEnabled: Bool!
    private var _electiveClusterName: String?
    private var _courseList: [Course]!

    var ClusterId: Int {
        return _electiveClusterId
    }

    var MultipleSelectionEnabled: Bool {
        return _multipleSelectionEnabled
    }

    var ElectiveClusterName: String? {
        if let elective = _electiveClusterName {
            return elective
        } else {
            return "Elective"
        }
    }

    var CourseList: [Course]? {
        return _courseList
    }

    required init?(map: Map){

    }

    func mapping(map: Map) {
        _electiveClusterId <- map["electiveClusterId"]
        _multipleSelectionEnabled <- map["multipleSelectionEnabled"]
        _electiveClusterName <- map["electiveClusterName"]
        _courseList <- map["coursesList"]
    }
}

class Course: Mappable {
    private var _courseId: Int!
    private var _courseName: String!
    private var _courseSelected: Bool!
    private var _classStarted: Bool!

    var CourseId: Int {
        return _courseId
    }

    var CourseName: String {
        return _courseName
    }

    var CourseSelected: Bool {
        return _courseSelected
    }

    var ClassStarted: Bool {
        return _classStarted
    }

    required init?(map: Map){

    }

    func mapping(map: Map) {
        _courseId <- map["courseId"]
        _courseName <- map["courseName"]
        _courseSelected <- map["selected"]
        _classStarted <- map["classStarted"]
    }
}

但由于某种原因，在我的responseObject中，我总是得到一个零对象。有人可以帮助我解决我的错误吗？

以下是获取回复的代码

func getElectivesCurriculumList(forProgramId programId: Int, batchYear: Int) {
        let url = "someurl"
        AlamofireManager.getAFSessionManager().request(url, method: .get, parameters: nil, encoding: URLEncoding.default, headers: nil).responseObject { (response: DataResponse<ElectivesMainResponse>) in
            print("Electives API URL: \(url)")
            switch response.result {
            case .success(_ ):

                if let value = response.result.value {
                    print("\(value.Res?.count)") //this is always nil
                    self.onGetElectivesResponse(value)
                }
                break
            case .failure(let error):
                print(error.localizedDescription)
                self.onGetElectivesFailure(error.localizedDescription)
                break
            }
        }
    }