How to make a struct model with this JSON? I've watched many tutorials on youtube but I'm still confused, and what's the meaning of using enum on struct?

{
  "err_code": 0,
  "data": {
    "message": "Success",
    "result": {
      "check_in": [
        {
          "created_at": "2022-06-20 10:00:37",
          "late": "True",
          "location": "Jl. H. Asmawi No.63, Beji, Kecamatan Beji, Kota Depok, Jawa Barat 16421, Indonesia",
          "place": "GRIT OFFICE",
          "folder": "./pegawai/grit/2022/06/20/masuk/10/00/",
          "filename": "0000_rakha_fatih_athallah_picture.jpg",
          "tujuan": "",
          "link": "http://103.140.90.10:8081/face-recognition/client/python/pegawai/grit/2022/06/20/masuk/10/00/0000_rakha_fatih_athallah_picture.jpg"
        },
        {
          "created_at": "2022-06-16 11:23:12",
          "late": "True",
          "location": "Jl. H. Asmawi No.63, Beji, Kecamatan Beji, Kota Depok, Jawa Barat 16421, Indonesia",
          "place": "GRIT OFFICE",
          "folder": "./pegawai/grit/2022/06/16/masuk/11/23/",
          "filename": "0000_rakha_fatih_athallah_picture.jpg",
          "tujuan": "",
          "link": "http://103.140.90.10:8081/face-recognition/client/python/pegawai/grit/2022/06/16/masuk/11/23/0000_rakha_fatih_athallah_picture.jpg"
        }
      ],
      "check_out": []
    }
  }
}

And this is my struct model. This is important because I want to use jsondecoder with this struct. I want using jsondecoder later.

import Foundation

struct jsonData : Codable{
    var err_code : Int
    var data : Data
    
    enum CodingKeys: String, CodingKey {
            case err_code = "err_code"
            case data = "data"
        }
}

struct Data: Codable{
    var message : String
    var result  : Result
}

struct Result : Codable {
    var check_in  : [Checkin] = []
}

struct Checkin : Codable{
    var created_at : String
    var late : String
    var location : String
    var place : String
    var folder : String
    var tujuan : String
    var link : String
    
    enum CodingKeys: String, CodingKey {
            case created_at = "created_at"
            case late = "late"
            case location = "location"
            case place = "place"
            case folder = "folder"
            case tujuan = "tujuan"
            case link = "link"
        }
}

CodePudding user response：

We use CodingKeys in order to use custom names for the ones in the JSON.

For example, you have created_at but you don't want the underscore, what you would do is name your variable createdAt and in the enum add case createdAt = "created_at"

As for the decoding part, it's actually pretty easy:

do {
    //let data = the json data you got.
    let decoder = JSONDecoder()
    let model = try decoder.decode(jsonData.self, from: data)
}catch {
    print(String(describing: error))
}

Please note that we don't use lowercase letters when naming structs, classes, actors & enums.

Edit: Thanks to Marek R for pointing out that sometimes the names in the JSON can match keywords specific to the used language (i.e: Swift), so it is necessary to implement CodingKeys.

CodePudding user response：

I think the structs you have are very close to what is required, just minor tweaks such as:

struct Response: Codable{
    var err_code: Int
    var data: DataObj
}

struct DataObj: Codable{
    var message: String
    var result: Result
}

struct Result: Codable {
    var check_in: [Checkin]
}

struct Checkin: Codable, Hashable {
    var created_at: String
    var late: String
    var location: String
    var place: String
    var folder: String
    var tujuan: String
    var link: String
}

Use it like this:

struct ContentView: View {
    @State var apiResponse: Response?
    
    var body: some View {
        VStack {
            if let response = apiResponse {
                Text("message: \(response.data.message) ")
                Text("check_in.count: \(response.data.result.check_in.count) ")
            List {
                ForEach(response.data.result.check_in, id: \.self) { chk in
                    Text("created_at: \(chk.created_at) ")
                }
            }
            }
        }
        .onAppear {
            let jsonStr = """
                 {
                 "err_code": 0,
                 "data": {
                 "message": "Success",
                 "result": {
                 "check_in": [
                 {
                 "created_at": "2022-06-20 10:00:37",
                 "late": "True",
                 "location": "Jl. H. Asmawi No.63, Beji, Kecamatan Beji, Kota Depok, Jawa Barat 16421, Indonesia",
                 "place": "GRIT OFFICE",
                 "folder": "./pegawai/grit/2022/06/20/masuk/10/00/",
                 "filename": "0000_rakha_fatih_athallah_picture.jpg",
                 "tujuan": "",
                 "link": "http://103.140.90.10:8081/face-recognition/client/python/pegawai/grit/2022/06/20/masuk/10/00/0000_rakha_fatih_athallah_picture.jpg"
                 },
                 {
                 "created_at": "2022-06-16 11:23:12",
                 "late": "True",
                 "location": "Jl. H. Asmawi No.63, Beji, Kecamatan Beji, Kota Depok, Jawa Barat 16421, Indonesia",
                 "place": "GRIT OFFICE",
                 "folder": "./pegawai/grit/2022/06/16/masuk/11/23/",
                 "filename": "0000_rakha_fatih_athallah_picture.jpg",
                 "tujuan": "",
                 "link": "http://103.140.90.10:8081/face-recognition/client/python/pegawai/grit/2022/06/16/masuk/11/23/0000_rakha_fatih_athallah_picture.jpg"
                 }
                 ],
                 "check_out": []
                 }
                 }
                 }
                 """
            // simulated response data
            let data = jsonStr.data(using: .utf8)!
            do {
                self.apiResponse = try JSONDecoder().decode(Response.self, from: data)
                print("\n---> apiResponse \(apiResponse)")
            }
            catch {
                print(" error \(error)")
            }
        }
    }
}