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使用Codable使用动态编码键解码json?

codable decode swift json

Said-Abdulla Atkaev · 技术社区 · 6 年前

我需要解码的Json示例。在“text”键中,我们有[String:String]指令,元素的数量是“count”。我应该如何正确地解码它?

{
"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"
}

我的可编码模型:

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))
    }
}

}

我用以下方法对其进行解码:

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.")
    }

我的代码有什么问题?这是解码这种动态编码键的好方法吗?

3 回复 | 直到 6 年前

Shehata Gamal 6 年前

你需要

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

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

Community kfsone 4 年前

修复JSON

我想你希望你的索引和计数是数字。所以换掉这个 "index": "1" "count": "4" 用这个 "index": 1 还有这个 "count": 4

阶级结构

对于可编码协议,这些编码键和编码函数或所需的初始化都不是必需的。同时将文本属性数据格式更改为[String:String]

因此,请按如下方式替换您的类:

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

要解码json,请使用上面所写的内容,这是正确的

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

Rob Napier 6 年前

您需要的最重要的东西是:

let text = try container.nestedContainer(keyedBy: CodingKeys.self, forKey: .text)
texts = try text.allKeys.map { try text.decode(String.self, forKey: $0) }

allKeys 是有序的(因为它是一个序列化协议)。

如果只符合以下条件,则不需要encode方法 Decodable 而不是 Codable . 而且,你的大多数期权都不是真正的期权。

把这些东西放在一起,你会发现:

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: $0) }
    }

}

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