SwiftUI macOS JSON 在 Codable 类中转换

Question

我从 api 调用中获得以下 json，但无法快速构建正确的结构，然后将数据作为数组获取。

JSON：

{
   "status":"ok",
   "users":[
      {
         "position":0,
         "user":{
            "pk":"",
            "full_name":"",
            "username":"",
            "profile_pic_url":""
         }
      },...
   ]
}

斯威夫特：

class Response: Codable {
    var status: String
    var users: [User]?
}

class User: Identifiable, Codable {
    var uuid = UUID()
    
    var pk: String
    var full_name: String
    var username: String
    var profile_pic_url: String
    
    enum CodingKeys: String, CodingKey {
        case
        pk = "user.pk",
        full_name = "user.full_name",
        username = "user.username",
        profile_pic_url = "user.profile_pic_url"
    }
}

class Fetch: ObservableObject {
    @Published var results = [User]()
    @Published var resultState = false
    @Published var errorState = false
    init(url: String) {
        self.results = []
        let url = URL(string: url)!
        URLSession.shared.dataTask(with: url) { data, response, error in
            do {
                if let data = data {
                    let results = try JSONDecoder().decode(Response.self, from: data)
                    DispatchQueue.main.async {
                        self.results = results.users ?? []
                        self.resultState = true
                    }
                    print("Widget: Ok.")
                } else {
                    self.results = []
                    self.resultState = true
                    print("Widget: No data.")
                }
            } catch {
                self.errorState = true
                self.resultState = true
                print("Widget: Error", error)
            }
        }.resume()
    }
}

代码：

@ObservedObject var fetch = Fetch(url: "")

List(fetch.results) { user in
    UserItem(user: user)
}

问题是在数组 users 里面，它包含一个对象，这个对象包含两个元素一个位置属性，然后是用户对象。

我认为我做错的是获取用户对象。

谁能帮帮我？

编辑：

struct Response: Codable {
    let status: String
    let users: [UserType]?
}

struct UserType: Codable {
    let position: Int
    let user: User
}

struct User: Codable {
    let pk: String
    let full_name: String
    let username: String
    let profile_pic_url: String
    enum CodingKeys: String, CodingKey {
        case pk, full_name, username, profile_pic_url
    }
}

class Fetch: ObservableObject {
    @Published var results = [User]()
    @Published var resultState = false
    @Published var errorState = false
    init(url: String) {
        self.results = []
        let url = URL(string: url)!
        URLSession.shared.dataTask(with: url) { data, response, error in
            do {
                if let data = data {
                    let results = try JSONDecoder().decode(Response.self, from: data)
                    let users = results.users?.map { $0.user }
                    DispatchQueue.main.async {
                        self.results = users ?? []
                        self.resultState = true
                    }
                    print("Widget: Ok.")
                } else {
                    self.results = []
                    self.resultState = true
                    print("Widget: No data.")
                }
            } catch {
                self.errorState = true
                self.resultState = true
                print("Widget: Error", error)
            }
        }.resume()
    }
}

        List(fetch.results) { user in
            UserItem(user: user)
        }

Answer 1

你可以试试这个。

    struct Response: Codable {
    let status: String 
    let users: [UserWPosition]
    
    var userNoPositions: [UserInfo] { // computed value with only array of userinfo
        users.compactMap { $0.user }
    }
}

// MARK: - User with position object
struct UserWPosition: Codable {
    let position: Int  // commenting this will also do no effect
    let user: UserInfo
}

// MARK: - UserInfo
struct UserInfo: Codable {
    let pk, fullName, username, profilePicURL: String
    enum CodingKeys: String, CodingKey {
        case pk
        case fullName = "full_name"
        case username
        case profilePicURL = "profile_pic_url"
    }
}

阅读我添加到代码解码中的 cmets 不会对未添加到 struct 的密钥进行编码，因此注释掉 position 也没有问题，它的层次结构现在应该是这样我添加了一个 @ 987654325@ 计算值以响应用户数组。
只需访问没有位置的数组

var resp =  try! JSONDecoder().decode(Response.self, from: encoded)  // encoded is the data from json   
print(resp.userNoPositions) // the array 

Answer 2

你需要一个额外的结构来保存用户类型

struct UserType: Codable {
    let position: Int
    let user: User
}

表示顶部类型变为

struct Response: Codable {
    let status: String
    let users: [UserType]?
}

您还需要更改 CodingKeys 枚举，因为它应该只包含属性名称，这意味着枚举可以写为

enum CodingKeys: String, CodingKey {
    case pk, full_name, username, profile_pic_url
}

为了完整起见，这里是完整的User 类型

struct User: Identifiable, Codable {
    var uuid = UUID()

    var pk: String
    var full_name: String
    var username: String
    var profile_pic_url: String

    enum CodingKeys: String, CodingKey {
        case pk, full_name, username, profile_pic_url
    }
}

解码时，您可以使用map 函数提取用户数组

do {
    let results = try JSONDecoder().decode(Response.self, from: data)
    let users = results.users?.map { $0.user }
    ....

请注意，我从 class 更改为 struct 因为 struct 更适合这个，但 class 也可以工作。我也想知道为什么users 属性是可选的，我没有改变它但是数组真的可以为零吗？