使用 Codable 使用动态编码密钥解码 json？

Question

示例 Json 我需要解码。在 "text" 键中，我们有 [String: String] 字典。元素的数量在 "count" 中。我应该如何正确解码？

{
"name": "LoremIpsum",
"index": "1",
"text": {
    "text_1": "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. ",
    "text_2": "Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. ",
    "text_3": "Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. ",
    "text_4": "Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.",
},
"count": "4"
}

我的 Codable 模型：

class Text: Codable {

private enum CodingKeys: String, CodingKey {
    case name, index, count, text
}

public var name: String?
public var index: Int?
public var count: Int?
public var texts: [String]?

init() {
    name = ""
    index = 0
    count = 0
    texts = []
}

init(name: String,
     index: Int,
     count: Int,
     texts: [String]) {
    self.name = name
    self.index = index
    self.count = count
    self.texts = texts
}

func encode(to encoder: Encoder) throws {
    var container = encoder.container(keyedBy: CodingKeys.self)
    var text = container.nestedContainer(keyedBy: CodingKeys.self, forKey: . text)

}    <---- also why do I need this method? 

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

    self.name = try container.decode(String.self, forKey: .name)
    self.index = Int(try container.decode(String.self, forKey: .index)) ?? 0
    self.count = Int(try container.decode(String.self, forKey: .count)) ?? 0
    let text = try container.nestedContainer(keyedBy: CodingKeys.self, forKey: .text)

    for i in (1...self.count!) {
        self.texts!.append(try text.decode(String.self, forKey: Text.CodingKeys.init(rawValue: "text_\(i)") ?? .text))
    }
}

}

然后我解码它：

if let path = Bundle.main.path(forResource: "en_translation_001", ofType: "json") {
        do {
            let data = try Data(contentsOf: URL(fileURLWithPath: path), options: .alwaysMapped)
            let jsonObj = try JSONDecoder().decode(Text.self, from: data)
            print("jsonData:\(jsonObj)")
        } catch let error {
            print("parse error: \(error.localizedDescription)")
        }
    } else {
        print("Invalid filename/path.")
    }

但是我遇到了解析错误

parse error: The data couldn’t be read because it is missing.

我的代码有什么问题？解码这种动态编码密钥是一种好方法吗？

Answer 1

修复JSON

我想您希望索引和计数是数字。所以替换这个 "index": "1" 和这个 "count": "4" 有了这个 "index": 1 和这个 "count": 4

Class结构

使用 Codable 协议，任何这些 CodingKeys 和编码函数或所需的初始化都不是必需的。同时将 texts 属性数据格式更改为 [String: String]

所以，像这样替换你的 class：

class Text: Codable {

    public var name: String
    public var index: Int
    public var count: Int
    public var texts: [String: String]

    init(name: String, index: Int, count: Int, texts: [String: String]) {
        self.name = name
        self.index = index
        self.count = count
        self.texts = texts
    }

}

解码

解码你的 json 使用你上面写的，这是正确的

let object = try JSONDecoder().decode(Text.self, from: data)

Answer 2

你需要

struct Root: Codable {
    let name, index,count: String
    let text: [String:String]
}

--

let res = try? JSONDecoder().decode(Root.self,from:jsonData)

Answer 3

你最需要的是这个：

let text = try container.nestedContainer(keyedBy: CodingKeys.self, forKey: .text)
texts = try text.allKeys.map { try text.decode(String.self, forKey: [=10=]) }

这会将字典转换为值数组。虽然原则上 JSON 值未排序，但 allKeys 已排序（因为它是序列化协议）。

如果您只符合 Decodable 而不是 Codable，则不需要编码方法。另外，你的大部分可选值都不是真正的可选值。

把这些东西放在一起，你会得到这个：

class Text: Decodable {

    private enum CodingKeys: String, CodingKey {
        case name, index, count, text
    }

    public var name: String
    public var index: Int
    public var count: Int
    public var texts: [String]

    init(name: String = "",
         index: Int = 0,
         count: Int = 0,
         texts: [String] = []) {
        self.name = name
        self.index = index
        self.count = count
        self.texts = texts
    }

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

        self.name = try container.decode(String.self, forKey: .name)
        self.index = Int(try container.decode(String.self, forKey: .index)) ?? 0
        self.count = Int(try container.decode(String.self, forKey: .count)) ?? 0
        let text = try container.nestedContainer(keyedBy: CodingKeys.self, forKey: .text)
        texts = try text.allKeys.map { try text.decode(String.self, forKey: [=11=]) }
    }

}

let jsonObj = try JSONDecoder().decode(Text.self, from: data)

使用 Codable 使用动态编码密钥解码 json？

Decode json with dynamic coding key using Codable?

json

decode

swift

codable

修复JSON

Class结构

解码