Swift 错误类型服务器响应来自 REST API 的错误输入

Question

希望你一切安好。我有个问题。我有一个带有电子邮件和密码的简单登录页面，还有一个类似的用户对象

// MARK: - UserModel
struct UserModel: Codable {
    let error: Bool
    let desc: String
    let user: User
    let token: String
}

// MARK: - User
struct User: Codable {
    let id: Int
    let email, firstName, lastName, lang: String
    let status: Int
    let referer, star: String?
    let phone: String?
    let ip: String?
    let birth, idNumber: String?
    let regionID: String?
    let createdAt, updatedAt: String

    enum CodingKeys: String, CodingKey {
        case id, email
        case firstName = "first_name"
        case lastName = "last_name"
        case lang, status, referer, star, phone, ip, birth
        case idNumber = "id_number"
        case regionID = "region_id"
        case createdAt, updatedAt
    }
}

返回类型是上一个（UserModel）。如果用户输入了他/她的凭据，则没有问题。但是，如果他/她输入了错误的凭据，麻烦就开始了。我无法解析来自服务器的返回值。总是给我那一行的错误。

控制台输出为：

Rentover[2343:150674] Fatal error: 'try!' expression unexpectedly raised an error: Swift.DecodingError.typeMismatch(Swift.Bool, Swift.DecodingError.Context(codingPath: [CodingKeys(stringValue: "error", intValue: nil)], debugDescription: "Expected to decode Bool but found a dictionary instead.", underlyingError: nil)): file

这是我的登录请求功能。为了简单起见，我使用了 codable。

class func requestLogIn(router: Router, completion: @escaping (Result<UserModel, Error>) -> ()) {

    guard let url = setUrlComponents(router: router).url else { return }
    var urlRequest = URLRequest(url: url)
    urlRequest.addValue("application/json", forHTTPHeaderField: "Content-Type")
    urlRequest.httpMethod = router.method

    if router.method == "POST"{
        let model = LoginModel(email: router.parameters[0], password: router.parameters[1])
        urlRequest.httpBody = try? JSONEncoder().encode(model)
    }

    let dataTask = URLSession.shared.dataTask(with: urlRequest) { data, response, error in

        guard error == nil else {
            print(error?.localizedDescription)
            return
        }
        guard response != nil else {
            print("no response")
            return
        }
        guard let data = data else {
            print("no data")
            return
        }

        let responseObject = try! JSONDecoder().decode(UserModel.self, from: data)
        print(responseObject.user)
        DispatchQueue.main.async {
            completion(.success(responseObject))
        }


    }
    dataTask.resume()
}

这是我的错误结构。

struct LogInError: Codable, Error{
    let error: Bool
    let desc: String
    let fields: [String] ----> 'Edit here old: let fileds: [String' 
}

最后我真正的调用函数是这样的

    NetworkService.requestLogIn(router: Router.login(email: nameTextField.text!, passowrd: passwordTextField.text!)) { (result) in
        switch result {
        case .success(let userModel):
            print("RESULT SUCCESS")
            print("Hello \(userModel.user.firstName)")

            let selectedVC = UIUtils.checkUserStatus(status: userModel.user.status)
            self.navigationController?.modalPresentationStyle = .fullScreen
            self.navigationController?.pushViewController(selectedVC, animated: true)
        case .failure(let error):
            print("RESULT FAILED")
            print(error)
        }
    }

我按照that medium 链接创建了我的路由器和网络服务。如果您能帮助我解决这个问题，我将非常高兴和感激。或者给我一些关于网络 API 和使用的建议。

[编辑来自服务器的错误响应] 我的请求和响应消息体框架也是这样的：

祝你有美好的一天。和良好的编码。

Answer 1

要解码两个不同的 JSON 字符串，一个方便的解决方案是使用关联类型的枚举，因为它可以非常具有描述性地表示 success 和 failure 情况。

首先它解码常见的error 密钥，然后解码UserModel 或LogInError

enum Response : Decodable {
    case success(UserModel), failure(LogInError)

    private enum CodingKeys : String, CodingKey { case error }

    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        let hasError = try container.decode(Bool.self, forKey: .error)
        if hasError {
            let errorContainer = try decoder.singleValueContainer()
            let errorData = try errorContainer.decode(LogInError.self)
            self = .failure(errorData)
        } else {
            let successContainer = try decoder.singleValueContainer()
            let successData = try successContainer.decode(UserModel.self)
            self = .success(successData)
        }
    }
}

使用它

class func requestLogIn(router: Router, completion: @escaping (Result<Response, Error>) -> ()) {

    ...

    do {
        let responseObject = try JSONDecoder().decode(Response.self, from: data)
        print(responseObject)
        DispatchQueue.main.async {
            completion(.success(responseObject))
        }
    } catch {
        DispatchQueue.main.async {
            completion(.failure(error))
        }
    }

和

NetworkService.requestLogIn(router: Router.login(email: nameTextField.text!, passowrd: passwordTextField.text!)) { (response) in
    switch response {
    case .success(let result):
        switch result {
            case .success(let userModel): 
                print("RESULT SUCCESS")
                print("Hello \(userModel.user.firstName)")

                let selectedVC = UIUtils.checkUserStatus(status: userModel.user.status)
                self.navigationController?.modalPresentationStyle = .fullScreen
                self.navigationController?.pushViewController(selectedVC, animated: true)
            case .failure(let errorData): 
                print(errorData)
        }

    case .failure(let error):
        print("RESULT FAILED")
        print(error)
    }
}

将LoginError 声明为标准的可解码结构

struct LogInError: Decodable {