如何解码具有不同类型的JSON属性？

Question

我有一个JSON

{
"tvShow": {
    "id": 5348,
    "name": "Supernatural",
    "permalink": "supernatural",
    "url": "http://www.episodate.com/tv-show/supernatural",
    "description": "Supernatural is an American fantasy horror television series created by Eric Kripke. It was first broadcast on September 13, 2005, on The WB and subsequently became part of successor The CW's lineup. Starring Jared Padalecki as Sam Winchester and Jensen Ackles as Dean Winchester, the series follows the two brothers as they hunt demons, ghosts, monsters, and other supernatural beings in the world. The series is produced by Warner Bros. Television, in association with Wonderland Sound and Vision. Along with Kripke, executive producers have been McG, Robert Singer, Phil Sgriccia, Sera Gamble, Jeremy Carver, John Shiban, Ben Edlund and Adam Glass. Former executive producer and director Kim Manners died of lung cancer during production of the fourth season.<br>The series is filmed in Vancouver, British Columbia and surrounding areas and was in development for nearly ten years, as creator Kripke spent several years unsuccessfully pitching it. The pilot was viewed by an estimated 5.69 million viewers, and the ratings of the first four episodes prompted The WB to pick up the series for a full season. Originally, Kripke planned the series for three seasons but later expanded it to five. The fifth season concluded the series' main storyline, and Kripke departed the series as showrunner. The series has continued on for several more seasons with Sera Gamble and Jeremy Carver assuming the role of showrunner.",
    "description_source": "http://en.wikipedia.org/wiki/Supernatural_(U.S._TV_series)#Spin-off_series",
    "start_date": "2005-09-13",
    "end_date": null,
    "country": "US",
    "status": "Running",
    "runtime": 60,
    "network": "The CW",
    "youtube_link": "6ZlnmAWL59I",
    "image_path": "https://static.episodate.com/images/tv-show/full/5348.jpg",
    "image_thumbnail_path": "https://static.episodate.com/images/tv-show/thumbnail/5348.jpg",
    "rating": "9.6747",
    "rating_count": "249",
    "countdown": null
}
}

rating不同系列中的值是Int（“ rating”：0）或String（“ rating”：“ 9.6747”）。

我正在使用Codable / Decodable协议解析JSON：

struct DetailModel : Decodable {

var id : Int?
var name : String?
var permalink : String?
var url : String?
var description : String
var description_source : String?
var start_date : String?
var end_date : String?
var country : String?
var status : String?
var runtime : Int?
var network : String?
var youtube_link : String?
var image_path : String?
var image_thumbnail_path : String?
var rating: String
var rating_count : String?
var countdown : String?
var genres : [String]?
var pictures : [String]?
var episodes : [EpisodesModel]?
}

如果rating == String，则我的代码有效，并且我具有JSON中的所有变量，但是如果rating ==
Int，则全部为nil。我应该怎么做来解析所有类型变量rating一次Int和String？

我的可解码功能：

    func searchSerialDetail(id: Int, completion: @escaping (DetailModel?) -> Void){

    let parameters: [String: Any] = ["q": id]

    Alamofire.request(DetailNetworkLayer.url, method: .get, parameters: parameters).response { (jsonResponse) in

        if let jsonValue =  jsonResponse.data {
            let jsonDecoder = JSONDecoder()
                let detail = try? jsonDecoder.decode(DetailModel.self, from: jsonValue)
                completion(detail)
        }
    }
}

谢谢。

Answer 1

您将必须实现自己的协议，func encode(to encoder: Encoder) throws并且init(from decoder: Decoder) throws这都是Codable协议的属性。然后将rating变量更改为 枚举

看起来像这样：

enum Rating: Codable {
    case int(Int)
    case string(String)

    func encode(to encoder: Encoder) throws {
        var container = encoder.singleValueContainer()
        switch self {
        case .int(let v): try container.encode(v)
        case .string(let v): try container.encode(v)
        }
    }

    init(from decoder: Decoder) throws {
        let value = try decoder.singleValueContainer()

        if let v = try? value.decode(Int.self) {
            self = .int(v)
            return
        } else if let v = try? value.decode(String.self) {
            self = .string(v)
            return
        }

        throw Rating.ParseError.notRecognizedType(value)
    }

    enum ParseError: Error {
        case notRecognizedType(Any)
    }
}

然后，您DetailModel只需更改rating: String为rating: Rating

这有效，我已经用这些JSON字符串进行了测试。

// int rating
{   
    "rating": 200,
    "bro": "Success"
}

// string rating
{
    "rating": "200",
    "bro": "Success"
}

编辑 ：我发现了一种更好的实现方法init(from decoder: Decoder) throws，它产生了更好的错误消息，通过使用此方法，您现在可以省略ParseError枚举。

init(from decoder: Decoder) throws {
    let value = try decoder.singleValueContainer()
    do {
        self = .int(try value.decode(Int.self))
    } catch DecodingError.typeMismatch {
        self = .string(try value.decode(String.self))
    }
}