如何使用Swift Decodable协议解码嵌套的JSON结构? [英] How to decode a nested JSON struct with Swift Decodable protocol?

问题描述

这是我的JSON

{
    "id": 1,
    "user": {
        "user_name": "Tester",
        "real_info": {
            "full_name":"Jon Doe"
        }
    },
    "reviews_count": [
        {
            "count": 4
        }
    ]
}

这是我想要保存到的结构(不完整)

Here is the structure I want it saved to (incomplete)

struct ServerResponse: Decodable {
    var id: String
    var username: String
    var fullName: String
    var reviewCount: Int

    enum CodingKeys: String, CodingKey {
       case id, 
       // How do i get nested values?
    }
}

我查看了 Apple的文档关于嵌套结构的解码，但是我仍然不了解如何正确执行JSON的不同级别.任何帮助将不胜感激.

I have looked at Apple's Documentation on decoding nested structs, but I still do not understand how to do the different levels of the JSON properly. Any help will be much appreciated.

推荐答案

另一种方法是创建一个与JSON紧密匹配的中间模型(借助于

Another approach is to create an intermediate model that closely matches the JSON (with the help of a tool like quicktype.io), let Swift generate the methods to decode it, and then pick off the pieces that you want in your final data model:

// snake_case to match the JSON and hence no need to write CodingKey enums / struct
fileprivate struct RawServerResponse: Decodable {
    struct User: Decodable {
        var user_name: String
        var real_info: UserRealInfo
    }

    struct UserRealInfo: Decodable {
        var full_name: String
    }

    struct Review: Decodable {
        var count: Int
    }

    var id: Int
    var user: User
    var reviews_count: [Review]
}

struct ServerResponse: Decodable {
    var id: String
    var username: String
    var fullName: String
    var reviewCount: Int

    init(from decoder: Decoder) throws {
        let rawResponse = try RawServerResponse(from: decoder)

        // Now you can pick items that are important to your data model,
        // conveniently decoded into a Swift structure
        id = String(rawResponse.id)
        username = rawResponse.user.user_name
        fullName = rawResponse.user.real_info.full_name
        reviewCount = rawResponse.reviews_count.first!.count
    }
}

如果将来它包含多个值，则还可以轻松地遍历reviews_count.

This also allows you to easily iterate through reviews_count, should it contain more than 1 value in the future.

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