ios - 快速将动态服务器响应转换为模型类

Question

以下是服务器响应处理父结构...

struct ServerResponse<T: Codable>: Codable {

    let status: Bool?
    let message: String?
    let data: T?

    enum CodingKeys: String, CodingKey {
        case status = "status"
        case message = "message"
        case data = "data"
    }

    init(from decoder: Decoder) throws {
        let values = try decoder.container(keyedBy: CodingKeys.self)
        status = try values.decodeIfPresent(Bool.self, forKey: .status)
        message = try values.decodeIfPresent(String.self, forKey: .message)
        data = try values.decodeIfPresent(T.self, forKey: .data)
    }
}

AppUserResponse结构:

struct AppUserResponse: Codable  {

    let accessToken : String?
    let askForMobileNo : Int?
    let tokenType : String?
    let user : AppUser?

    enum CodingKeys: String, CodingKey {
        case accessToken = "access_token"
        case askForMobileNo = "ask_for_mobile_no"
        case tokenType = "token_type"
        case user = "user"
    }

    init(from decoder: Decoder) throws {
        let values = try decoder.container(keyedBy: CodingKeys.self)
        accessToken = try values.decodeIfPresent(String.self, forKey: .accessToken)
        askForMobileNo = try values.decodeIfPresent(Int.self, forKey: .askForMobileNo)
        tokenType = try values.decodeIfPresent(String.self, forKey: .tokenType)
        user = try values.decodeIfPresent(AppUser.self, forKey: .user)
    }

}

struct AppUser: Codable {

    let createdAt : String?
    let deviceToken : String?
    let deviceType : String?
    let email : String?
    let emailVerifiedAt : String?
    let firstName : String?
    let id : Int?
    let lastName : String?
    let mobile_no : String?
    let mobileVerified : Int?
    let mobileVerifiedAt : String?
    let provider : String?
    let providerId : String?
    let status : Int?
    let updatedAt : String?

    enum CodingKeys: String, CodingKey {
        
        case createdAt = "created_at"
        case deviceToken = "device_token"
        case deviceType = "device_type"
        case email = "email"
        case emailVerifiedAt = "email_verified_at"
        case firstName = "first_name"
        case id = "id"
        case lastName = "last_name"
        case mobile_no = "mobile_no"
        case mobileVerified = "mobile_verified"
        case mobileVerifiedAt = "mobile_verified_at"
        case provider = "provider"
        case providerId = "provider_id"
        case status = "status"
        case updatedAt = "updated_at"
       
    }

    init(from decoder: Decoder) throws {
        let values = try decoder.container(keyedBy: CodingKeys.self)
        createdAt = try values.decodeIfPresent(String.self, forKey: .createdAt)
        deviceToken = try values.decodeIfPresent(String.self, forKey: .deviceToken)
        deviceType = try values.decodeIfPresent(String.self, forKey: .deviceType)
        email = try values.decodeIfPresent(String.self, forKey: .email)
        emailVerifiedAt = try values.decodeIfPresent(String.self, forKey: .emailVerifiedAt)
        firstName = try values.decodeIfPresent(String.self, forKey: .firstName)
        id = try values.decodeIfPresent(Int.self, forKey: .id)
        lastName = try values.decodeIfPresent(String.self, forKey: .lastName)
        mobile_no = try values.decodeIfPresent(String.self, forKey: .mobile_no)
        mobileVerified = try values.decodeIfPresent(Int.self, forKey: .mobileVerified)
        mobileVerifiedAt = try values.decodeIfPresent(String.self, forKey: .mobileVerifiedAt)
        provider = try values.decodeIfPresent(String.self, forKey: .provider)
        providerId = try values.decodeIfPresent(String.self, forKey: .providerId)
        status = try values.decodeIfPresent(Int.self, forKey: .status)
        updatedAt = try values.decodeIfPresent(String.self, forKey: .updatedAt)
    }

}

TempUserResponse结构

struct TempUserResponse : Codable {

    let askForMobileNo : Int?
    let provider : String?
    let providerId : String?
    let tempUser : TempUser?

    enum CodingKeys: String, CodingKey {
        case askForMobileNo = "ask_for_mobile_no"
        case provider = "provider"
        case providerId = "provider_id"
        case tempUser = "temp_user"
    }

    init(from decoder: Decoder) throws {
        let values = try decoder.container(keyedBy: CodingKeys.self)
        askForMobileNo = try values.decodeIfPresent(Int.self, forKey: .askForMobileNo)
        provider = try values.decodeIfPresent(String.self, forKey: .provider)
        providerId = try values.decodeIfPresent(String.self, forKey: .providerId)
        tempUser = try values.decodeIfPresent(TempUser.self, forKey: .tempUser)
    }

}


struct TempUser : Codable {

    let email : String?
    let name : String?

    enum CodingKeys: String, CodingKey {
        case email = "email"
        case name = "name"
    }

    init(from decoder: Decoder) throws {
        let values = try decoder.container(keyedBy: CodingKeys.self)
        email = try values.decodeIfPresent(String.self, forKey: .email)
        name = try values.decodeIfPresent(String.self, forKey: .name)
    }

}

问题

在应用程序中，我们有 2 个按钮，1. FB 登录和 2. Google 登录

当我尝试使用新用户登录时，服务器返回此响应(此时用户未注册，所以我在“数据”中得到“tempUser”)

    {
      "status": true,
      "message": "User social email address verified, mobile number unverified!.",
      "data": {
        "temp_user": {
          "name": "dhaval solanki",
          "email": "dhaval.sassyinfotech@gmail.com"
        },
        "provider": "google",
        "provider_id": "112620316711299944315",
        "ask_for_mobile_no": 1
      }
    }

当我使用注册用户登录时，我收到以下响应...

  {
    "status": true,
    "message": "User logged in successfully.",
    "data": {
      "user": {
        "id": 60,
        "first_name": "Ankit",
        "last_name": "Joshi",
        "mobile_no": "9876543211"
      },
      "access_token": "eyJLCJhbGciOiJIUzI1NR..",
      "token_type": "bearer",
      "ask_for_mobile_no": 0
    }
 }

使用以下将响应转换为模型类(我使用 Alamofire 进行 api 调用)

  let decoder = JSONDecoder()
  do {

      let responseData = try decoder.decode(ServerResponse <TempUserResponse>.self, from: serverData)
      success(responseData as AnyObject)
  } catch {
      print("Error = \(error)")
      do {
          let responseData = try decoder.decode(ServerResponse<AppUserResponse>.self, from: serverData)
          success(responseData as AnyObject)
      } catch {
          failure(error.localizedDescription as AnyObject)
      }
  }

当我运行此代码时，它总是会尝试将响应转换为 ServerResponse<TempUserResponse>即使响应的类型为 ServerResponse<AppUserResponse> .
那么如何通过将响应转换为受人尊敬的模型类来管理这两种响应呢？

Answer 1

您的 JSON 响应的解码总是在第一次尝试中成功(使用 TempUserResponse 类型)，因为您的所有属性都是可选的并且使用 decodeIfPresent<T>(_:forKey:) 解码功能。
所以，JSONDecoder假设键的值 data在您的根对象中是 TempUserResponse实例，但所有属性都设置为 nil . (JSON 中不存在任何属性键)
为了避免这种行为，您可以设置一个对您有意义的属性，在 TempUserResponse 中是强制性的。 ，例如 tempUser :

struct TempUserResponse : Codable {
    let askForMobileNo: Int?
    let provider: String?
    let providerId: String?
    let tempUser: TempUser

    enum CodingKeys: String, CodingKey {
        case askForMobileNo = "ask_for_mobile_no"
        case provider = "provider"
        case providerId = "provider_id"
        case tempUser = "temp_user"
    }

    init(from decoder: Decoder) throws {
        let values = try decoder.container(keyedBy: CodingKeys.self)
        askForMobileNo = try values.decodeIfPresent(Int.self, forKey: .askForMobileNo)
        provider = try values.decodeIfPresent(String.self, forKey: .provider)
        providerId = try values.decodeIfPresent(String.self, forKey: .providerId)
        tempUser = try values.decode(TempUser.self, forKey: .tempUser)
    }
}

如果 tempUser key 存在于 JSON 中，如果不存在则会失败并回退到 AppUserResponse解码。
更新 :另一种解决方案是将两个结构合并为一个，并将其所有属性作为可选项。
这样你的模型会简单很多:

struct UserResponse: Codable  {
    let accessToken: String?
    let askForMobileNo: Int?
    let tokenType: String?
    let user: AppUser?
    
    let provider: String?
    let providerId: String?
    let tempUser: TempUser?

    enum CodingKeys: String, CodingKey {
        case accessToken = "access_token"
        case askForMobileNo = "ask_for_mobile_no"
        case tokenType = "token_type"
        case user = "user"
        
        case provider = "provider"
        case providerId = "provider_id"
        case tempUser = "temp_user"
    }

    init(from decoder: Decoder) throws {
        let values = try decoder.container(keyedBy: CodingKeys.self)
        accessToken = try values.decodeIfPresent(String.self, forKey: .accessToken)
        askForMobileNo = try values.decodeIfPresent(Int.self, forKey: .askForMobileNo)
        tokenType = try values.decodeIfPresent(String.self, forKey: .tokenType)
        user = try values.decodeIfPresent(AppUser.self, forKey: .user)
        
        provider = try values.decodeIfPresent(String.self, forKey: .provider)
        providerId = try values.decodeIfPresent(String.self, forKey: .providerId)
        tempUser = try values.decodeIfPresent(TempUser.self, forKey: .tempUser)
    }
}

注意:不包括未更改的结构。
解码代码将如下所示:

let decoder = JSONDecoder()
do {
    let responseData = try decoder.decode(ServerResponse<UserResponse>.self, from: Data(jsonString.utf8))
    print(responseData)
} catch {
    print(error)
}

你可以检查一下 user或 tempUser属性(property)存在以确定您的情况。