使用 decodable 在单行中捕获嵌套对象数组

Question

下面是我的 json 响应和我需要从中构建的结构。

条件：我不想创建除 Response,Media 之外的任何其他结构，并且希望按照下面指定的方式在单行中进行解析。

{
     "name": "xxxx",
     "title": "xxxxxxx",
     "assets": [
        {
          "items": [
            {
              "id": "eeee",
              "desc": "rrrrrr"
            },            {
              "id": "eeee",
            },            {
              "desc": "rrrrrr"
            }]
        }]
}



struct Response {
    let name  : String
    let title : string
    let items : [Media]

    private enum codingKeys : String, CodingKey {
        case name = "name"
        case title = "title"
        case items = "assets.items"
    }

    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: codingKeys.self)
        name = try container.decode(String.self, forKey: .name)
        title = try container.decode(TrayLayout.self, forKey: .title)
        items = try container.decode([Media].self, forKey: .items)
    }
}

Answer 1

你可以试试这个：

struct Response: Decodable {
  let name, title: String
  let assets: [Assets]
}

struct Assets: Decodable {
 let items: [Items]
}

struct Items: Decodable {
  let id, desc: String
}

然后你就可以这样解码了：

guard let response = try? JSONDecoder().decode(Response.self, from: data) else { print("Response not parsed"); return }

Answer 2

我设法找到了解决您问题的方法。

考虑以下是示例 json

let jsonString = """
{
     "name": "xxxx",
     "title": "xxxxxxx",
     "assets": [
        {
          "items": [
            {
              "id": "id11",
              "desc": "desc11"
            },            {
              "id": "id12",
            },            {
              "desc": "desc13"
            }]
        },{
          "items": [
            {
              "id": "id21",
              "desc": "desc21"
            },            {
              "id": "id22",
            },            {
              "desc": "desc23"
            }]
        }]
}
"""

您的结构如下所示

struct Media: Codable {
    let id,desc: String?
    enum CodingKeys: String, CodingKey {
        case id,desc
    }
}

struct Response: Decodable {
    let name,title: String?
    let items: [Media]?
    enum CodingKeys: String, CodingKey {
        case name,title,items
        case assets = "assets"
    }
    // Decoding
    init(from decoder: Decoder) throws {

        let container = try decoder.container(keyedBy: CodingKeys.self)
        name = try container.decode(String.self, forKey: .name)
        title = try container.decode(String.self, forKey: .title)

        // Here as the assets contains array of object which has a key as items and then again consist of a array of Media we need to decode as below
        let assets = try container.decode([[String:[Media]]].self, forKey: .assets)

        // At this stage will get assets with a array of array so we first map and retrive the items and then reduce them to one single array
        items = assets.compactMap{[=11=][CodingKeys.items.rawValue]}.reduce([], +)
    }
}

最后是时候如下使用了

let data = jsonString.data(using: .utf8)!
let myResponse = try! JSONDecoder().decode(Response.self, from: data)

现在您可以访问如下数据

myResponse.name
myResponse.title
myResponse.items

希望这个基本代码能帮助您实现您想要做的事情。然后你可以继续做更多的嵌套解析。

感谢 Nic Laughter such a detailed article；通过参考我设法提供了上述解决方案。

Answer 3

找到新方法：

struct Media: Codable {
    let id,desc: String?
    enum CodingKeys: String, CodingKey {
        case id,desc
    }
}
struct Response: Decodable, CustomStringConvertible {
    let name,title: String?
    @NestedKey
    let items: [Media]?
    enum CodingKeys: String,NestableCodingKey {
        case name,title,
        case items = "assets/items"
    }

}

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