使用 Codable 解析任何类型的 json

Question

如果这个问题被多次回答，我很抱歉，但我正在寻找我自己的特定 json 问题，这就是为什么发布这个，这是我的 json，它是一个通知数组列表，在额外的对象中你可以看到它有合同对象, 现在这个对象正在改变它可以是 json 数组的第二个索引中的活动或反馈我如何制作 Codable 结构来解码这种类型的 json 这是我的结构，我不能在 Codable 中做任何类型

struct Alert: Decodable { var id: Int? var isUnread: Bool? var userId: Int? var message: String? var notificationType: String? var extra: Any?

 "value": [
        {
            "id": 153,
            "is_unread": true,
            "user_id": 3,
            "message": "Contract offered from JohnWick. Click here to see the details.",
            "notification_type": "Contract",
            "extra": {
                "contract": {
                    "id": 477,
                    "likes": 0,
                    "shares": 0,
                    "account_reach": 0.0,
                    "followers": 0,
                    "impressions": 0.0,
                    "description": "Fsafasd",
                    "budget": 0.0,
                    "start_date": null,
                    "end_date": null,
                    "status": "pending",
                    "is_accepted": false,
                    "brand_id": 443,
                    "influencer_id": 3,
                    "proposal_id": 947,
                    "created_at": "2019-11-09T17:40:57.646Z",
                    "updated_at": "2019-11-09T17:40:57.646Z",
                    "contract_fee": 435345.0,
                    "base_fee": 5000.0,
                    "transaction_fee": 43534.5,
                    "total_fee": 483879.5,
                    "infuencer_completed": false,
                    "brand_completed": false,
                    "comments": 0
                }
            }
        },
{
            "id": 152,
            "is_unread": true,
            "user_id": 3,
            "message": "Message from JohnWick. Click here to check your inbox.",
            "notification_type": "Message",
            "extra": {
                "message": {
                    "id": 495,
                    "body": "Uuhvh",
                    "read": false,
                    "conversation_id": 42,
                    "user_id": 3,
                    "created_at": "2019-11-08T13:44:02.055Z",
                    "updated_at": "2019-11-08T13:44:02.055Z"
                }
            }
        },
    ]

如您所见，它可以是消息、活动、合同或反馈，那么我如何使用 CodingKeys Codable 解析或为此建模

Answer 1

一个简单的解决方案是创建一个名为Extra 的结构，它为您拥有的每种情况提供四个可选属性。

struct Extra: Codable {
    let contract: Contract?
    let message: Message?
    let feedback: Feedback?
    let campaign: Campaign?
}

只要每个消息、活动、合同和反馈都有固定的响应，那么您应该能够为它们创建符合Codable 的结构。

Answer 2

你在这里不是指Any。正如您所说，extra 可以是“消息、活动、合同或反馈”。它不能是 UIViewController 或 CBPeripheral。这不是“任何东西”。这是四件事之一。

"One of X things" 是一个枚举：

enum Extra {
    case contract(Contract)
    case campaign(Campaign)
    case message(Message)
    case feedback(Feedback)
}

要使其可解码，我们只需要寻找正确的密钥：

extension Extra: Decodable {
    enum CodingKeys: CodingKey {
        case contract, campaign, message, feedback
    }

    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)

        // Try to decode each thing it could be; throw if nothing matches.
        if let contract = try? container.decode(Contract.self, forKey: .contract) {
            self = .contract(contract)
        } else if let campaign = try? container.decode(Campaign.self, forKey: .campaign) {
            self = .campaign(campaign)
        } else if let message = try? container.decode(Message.self, forKey: .message) {
            self = .message(message)
        } else if let feedback = try? container.decode(Feedback.self, forKey: .feedback) {
            self = .feedback(feedback)
        } else {
            throw DecodingError.valueNotFound(Self.self,
                                              DecodingError.Context(codingPath: container.codingPath,
                                                                    debugDescription: "Could not find extra"))
        }
    }
}

Answer 3

在这篇文章中，你可以找到一种支持任何类型的可编码方式，因此 JSON 返回 String 或 Int 无关紧要：

anycodableValue

Answer 4

这不是Any 类型，你有四种不同但可预测的类型。

参考 Rob 的回答，如果您将 notificationType 解码为枚举并根据其值解码子类型，则可以摆脱 if - else if 链中的解码尝试

enum NotificationType : String, Decodable {
    case contract = "Contract", message = "Message",  campaign = "Campaign", feedback = "Feedback"
}

enum Extra {
    case contract(Contract)
    case campaign(Campaign)
    case message(Message)
    case feedback(Feedback)
}

struct Alert: Decodable {
    let id: Int
    let isUnread: Bool
    let userId: Int
    let message: String
    let notificationType: NotificationType
    let extra: Extra
    
    private enum CodingKeys : String, CodingKey { case id, isUnread, userId, message, notificationType, extra}
    
    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        id = try container.decode(Int.self, forKey: .id)
        isUnread = try container.decode(Bool.self, forKey: .isUnread)
        userId = try container.decode(Int.self, forKey: .userId)
        message = try container.decode(String.self, forKey: .message)
        notificationType = try container.decode(NotificationType.self, forKey: .notificationType)
        switch notificationType {
            case .contract:
                let contractData = try container.decode([String:Contract].self, forKey: .extra)
                extra = .contract(contractData[notificationType.rawValue.lowercased()]!)
            case .campaign:
                let campaignData = try container.decode([String:Campaign].self, forKey: .extra)
                extra = .campaign(campaignData[notificationType.rawValue.lowercased()]!)
            case .message:
                let messageData = try container.decode([String:Message].self, forKey: .extra)
                extra = .message(messageData[notificationType.rawValue.lowercased()]!)
            case .feedback:
                let feedbackData = try container.decode([String:Feedback].self, forKey: .extra)
                extra = .feedback(feedbackData[notificationType.rawValue.lowercased()]!)
        }
    }
}