尝试使用 Alamofire 解析 API 响应时出错

Question

API 响应：

{
    "data": {
        "customer_id": "fb5056fe-d7cf-4b5e-3e32-08d9568a3822",
        "source": "self",
        "type": "customer",
        "language": "en",
        "identity_card": {
            "first_name": "abdulrahman",
            "middle_name": "ahmed",
            "last_name": "ali",
            "localized_first_name": "abdulrahman",
            "localized_middle_name": "ahmed",
            "localized_last_name": "ali",
            "identity_card_number_last_digits": "4416",
            "date_of_birth": "1994-05-15T00:00:00",
            "date_of_birth_calendar_type": "gregorian"
        },
        "income": [],
        "identity_verifications": [
            null
        ],
        "is_identity_verification_complete": false,
        "is_address_complete": false,
        "is_income_complete": false,
        "is_usage_complete": false,
        "is_employment_complete": false,
        "customer_status": 3,
        "customer_status_description": "inactive",
        "wallet_status": 0,
        "wallet_status_description": "pending"
    }
}

我的模特：

struct cst_Value : Codable {
    
    let address : cst_Addres?
    let employment : cst_Employment?
    let income : [cst_Income]?
    let usage : cst_Usage?
    let identityVerification : [cst_IdentityVerification]?
    
    let customer_id : String?
    let source : String?
    let type : String?
    let language : String?
    let email : String?
    let phone_number : String?
    let identity_card : cst_IdentityCard?
    let is_identity_verification_complete : Bool?
    let is_address_complete : Bool?
    let is_income_complete : Bool?
    let is_usage_complete : Bool?
    let is_employment_complete : Bool?
    let status : String?
    
    enum CodingKeys: String, CodingKey {
        case customer_id = "customer_id"
        case source = "source"
        case type = "type"
        case language = "language"
        case email = "email"
        case phone_number = "phone_number"
        case identity_card = "identity_card"
        case is_identity_verification_complete = "is_identity_verification_complete"
        case is_address_complete = "is_address_complete"
        case is_income_complete = "is_income_complete"
        case is_usage_complete = "is_usage_complete"
        case is_employment_complete  = "is_employment_complete"
        case status = "status"
        
        case address = "address"
        case employment = "employment"
        case income = "income"
        case usage = "usage"
        case identityVerification = "identity_verifications"
    }
    
    init(from decoder: Decoder) throws {
        let values = try decoder.container(keyedBy: CodingKeys.self)
        customer_id = try values.decodeIfPresent(String.self, forKey: .customer_id)
        source = try values.decodeIfPresent(String.self, forKey: .source)
        type = try values.decodeIfPresent(String.self, forKey: .type)
        language = try values.decodeIfPresent(String.self, forKey: .language)
        email = try values.decodeIfPresent(String.self, forKey: .email)
        phone_number = try values.decodeIfPresent(String.self, forKey: .phone_number)
        identity_card = try values.decodeIfPresent(cst_IdentityCard.self, forKey: .identity_card)
        is_identity_verification_complete = try values.decodeIfPresent(Bool.self, forKey: .is_identity_verification_complete)
        is_address_complete = try values.decodeIfPresent(Bool.self, forKey: .is_address_complete)
        is_income_complete = try values.decodeIfPresent(Bool.self, forKey: .is_income_complete)
        is_usage_complete = try values.decodeIfPresent(Bool.self, forKey: .is_usage_complete)
        is_employment_complete = try values.decodeIfPresent(Bool.self, forKey: .is_employment_complete)
        status = try values.decodeIfPresent(String.self, forKey: .status)
        address = try values.decodeIfPresent(cst_Addres.self, forKey: .address)
        employment = try values.decodeIfPresent(cst_Employment.self, forKey: .employment)
        income = try values.decodeIfPresent([cst_Income].self, forKey: .income)
        usage = try values.decodeIfPresent(cst_Usage.self, forKey: .usage)
        identityVerification = try values.decodeIfPresent([cst_IdentityVerification].self, forKey: .identityVerification)
    }
}

struct cst_IdentityVerification : Codable {

    let identityVerificationMethod : String?
    let identityVerificationStatus : String?


    enum CodingKeys: String, CodingKey {
        case identityVerificationMethod = "identity_verification_method"
                case identityVerificationStatus = "identity_verification_status"
    }
    init(from decoder: Decoder) throws {
        let values = try decoder.container(keyedBy: CodingKeys.self)
        identityVerificationMethod = try values.decodeIfPresent(String.self, forKey: .identityVerificationMethod)
        identityVerificationStatus = try values.decodeIfPresent(String.self, forKey: .identityVerificationStatus)
    }


}

错误：

▿ Optional<AFError>
  ▿ some : AFError
    ▿ responseSerializationFailed : 1 element
      ▿ reason : ResponseSerializationFailureReason
        ▿ decodingFailed : 1 element
          ▿ error : DecodingError
            ▿ valueNotFound : 2 elements
              - .0 : Swift.KeyedDecodingContainer<MobilePay.cst_IdentityVerification.CodingKeys>
              ▿ .1 : Context
                ▿ codingPath : 3 elements
                  - 0 : CodingKeys(stringValue: "data", intValue: nil)
                  - 1 : CodingKeys(stringValue: "identity_verifications", intValue: nil)
                  ▿ 2 : _JSONKey(stringValue: "Index 0", intValue: 0)
                    - stringValue : "Index 0"
                    ▿ intValue : Optional<Int>
                      - some : 0
                - debugDescription : "Cannot get keyed decoding container -- found null value instead."
                - underlyingError : nil

Answer 1

这里有很多问题。主要的一个是您拥有具有三层数据的 json，并且您将其视为一个平面结构。你在这里有两个选择。您可以通过手动解开 init(decoder:) 中的所有嵌套级别并手动处理容器来使其适合您现有的数据结构，但更简单的方法是在您的数据结构中建模 json 并允许 Decodable 为您完成.

您拥有的第一级是顶级data 字典。您可以创建一个包装结构来解码：

struct Wrapper: Codable {
   let data: cst_Value
}

然后你需要定义 cst_Value 结构体（注意 Swift 约定是所有类型都应该以大写字母开头）。这与您之前的类似，但由于我们现在依赖于 Decodable，您不需要定义 CodingKeys 或初始化程序。

struct cst_Value : Codable {
   
   let address : cst_Addres?
   let employment : cst_Employment?
   let income : [cst_Income]?
   let usage : cst_Usage?
   let identityVerification : [cst_IdentityVerification?]?
   
   let customer_id : String?
   let source : String?
   let type : String?
   let language : String?
   let email : String?
   let phone_number : String?
   let identity_card : cst_IdentityCard?
   let is_identity_verification_complete : Bool?
   let is_address_complete : Bool?
   let is_income_complete : Bool?
   let is_usage_complete : Bool?
   let is_employment_complete : Bool?
   let status : String?

其中许多字段不存在于您的 JSON 中，但我将它们保留在其中，因为它们是可选的并且可能（？）存在于某些未来的 json 中。如果它们将保持未使用状态，请移除它们。

还要注意定义的变化

   let identity_verifications : [cst_IdentityVerification?]?

由于我删除了 CodingKeys 枚举，我已将属性名称更改为与 json 键相同的名称（但请注意我的最后一段关于此的内容，以及您可能想要恢复它的原因）。

这里的json结构是一个带有可选元素的非可选数组，所以数组持有的类型需要是可选的。数组本身也需要是可选的，因为您使用的是decodeIfPresent，因此如果 json 中没有它的条目，它需要能够接受 nil。

最后，json 中未被处理的第三层是identity_card 的条目。为了支持这一点，需要一个适当的类型：

struct cst_IdentityCard: Codable {
   let first_name: String
   let middle_name: String
   let last_name: String
   let localized_first_name: String
   let localized_middle_name: String
   let localized_last_name: String
   let identity_card_number_last_digits: String
   let date_of_birth: String
   let date_of_birth_calendar_type: String
}

一旦所有这些组件就位，您就可以解码Wrapper 类型，然后从其data 字段中提取您想要的数据：

let decoder = JSONDecoder()
let jsonData = json.data(using: .utf8)!
do {
   let output = try decoder.decode(Wrapper.self, from: jsonData)
   print(output)
} catch {
   print(error)
}

这样做会成功解码，输出为：

Wrapper(data: __lldb_expr_12.cst_Value(address: nil, employment: nil,
income: Optional([]), usage: nil, identityVerification: nil, customer_id: 
Optional("fb5056fe-d7cf-4b5e-3e32-08d9568a3822"), source: 
Optional("self"), type: Optional("customer"), language: Optional("en"), email: nil, phone_number: nil, identity_card: 
Optional(__lldb_expr_12.cst_IdentityCard(first_name: "abdulrahman", 
middle_name: "ahmed", last_name: "ali", localized_first_name: 
"abdulrahman", localized_middle_name: "ahmed", localized_last_name: "ali", 
identity_card_number_last_digits: "4416", date_of_birth: "1994-05-
15T00:00:00", date_of_birth_calendar_type: "gregorian")), 
is_identity_verification_complete: Optional(false), is_address_complete: 
Optional(false), is_income_complete: Optional(false), is_usage_complete: 
Optional(false), is_employment_complete: Optional(false), status: nil))

注意这里还有很多 nil 值，因为很多字段没有在 json 中定义。

如果您愿意，您可以将其处理成扁平的数据结构。

虽然涉及更多数据类型，但这种方法更易于编码和管理，因为Decodable 为您完成大部分工作，您不必担心CodingKeys 或init(decoder:)

您可能要考虑的另一件事是重新引入 CodingKeys 枚举并使用它来将更多“Swifty”属性名称映射到 json 键。

Answer 2

错误信息中给出了问题的根源

• 1 : CodingKeys(stringValue: "identity_verifications", intValue: nil)

这应该会提示您检查该数据结构和相关联的 JSON。

属性定义为

let identityVerification : [cst_IdentityVerification]?

所以，cst_IdentityVerification 元素的可选数组。

然而 JSON 是

"identity_verifications": [
            null
        ],

所以是一个带有可选元素的非可选数组。

这不一样。定义中的数组是可选的，数据中的数组是非可选的，但有一个元素是可选的。

查看JSON你需要的数据结构

let identityVerification : [cst_IdentityVerification?]

虽然如果数组本身有可能为零，您将需要

let identityVerification : [cst_IdentityVerification?]?