在Swift中使用可編碼解析JSON

Question

我正在嘗試在Swift中使用可編碼的方式解析JSON。 我之前已經成功完成了此操作，但是我有一個帶有一些數組的更復雜的JSON對象，遇到了麻煩。

這是我的JSON：

{
"data": [ {
    "type":"player",
    "id":"account.7e5b92e6612440349afcc06b7c390114",
    "attributes": {
        "createdAt":"2018-04-06T04:59:40Z",
        "name":"bob",
        "patchVersion":"",
        "shardId":"pc-na",
        "stats":null,
        "titleId":"bluehole-pubg",
        "updatedAt":"2018-04-06T04:59:40Z"
    },
    "relationships": {
        "assets": {
            "data":[]
        },
        "matches": {
            "data": [
            {"type":"match","id":"3e2a197a-1453-4569-b35b-99e337dfabc5"},
            {"type":"match","id":"15f41d2f-9da2-4b95-95ca-b85e297e14b7"},
            {"type":"match","id":"a42c496c-ad92-4d3e-af1f-8eaa2e200c2b"}
            {"type":"match","id":"b6e33df5-4754-49da-9a0f-144842bfc306"},
            {"type":"match","id":"5b357cd1-35fe-4859-a2d7-48f263120bbd"},
            {"type":"match","id":"99fc5f81-c24c-4c82-ae03-cd21c94469c0"},
            {"type":"match","id":"1851c88e-6fed-48e8-be84-769f20f5ee6f"},
            {"type":"match","id":"e16db7ea-520f-4db0-b45d-649264ac019c"},
            {"type":"match","id":"6e61a7e7-dcf5-4df5-aa88-89eca8d12507"},
            {"type":"match","id":"dcbf8863-9f7c-4fc9-b87d-93fe86babbc6"},
            {"type":"match","id":"0ba20fbb-1eaf-4186-bad5-5e8382558564"},
            {"type":"match","id":"8b104f3b-66d5-4d0a-9992-fe053ab4a6ca"},
            {"type":"match","id":"79822ea7-f204-47f8-ae6a-7efaac7e9c90"},
            {"type":"match","id":"1389913c-a742-434a-80c5-1373e115e3b6"}
            ]
        }
    },
    "links": {
        "schema":"",
        "self":"https://api.playbattlegrounds.com/shards/pc-na/players/account.7e5b92e6612440349afcc06b7c390114"
    }
}],
"links": {
    "self":"https://api.playbattlegrounds.com/shards/pc-na/players?filter[playerNames]=dchilds64"
    },
"meta":{}
}

這是我正在使用的模型：

public struct PlayerResponse: Codable {
    let data: [Player]
}

對於玩家：

public struct Player: Codable {
    let type: String
    let id: String
    let attributes: Attributes
    let relationships: Relationships
}

對於屬性：

public struct Attributes: Codable {
    let name: String
    let patchVersion: String
    let shardId: String
    let titleId: String
    let updatedAt: String
}

對於關系：

public struct Relationships: Codable {
    let matches: Matches
}

對於比賽：

public struct Matches: Codable {
    let data: [Match]
}

匹配：

public struct Match: Codable {
    let type: String
    let id: String

}

解碼為：

let players = try decoder.decode([Player].self, from: jsonData)

我有運行我的網絡請求的此功能：

    func getPlayerData(for name: String, completion: ((Result<[Player]>) -> Void)?) {
    var urlComponents = URLComponents()
    urlComponents.scheme = "https"
    urlComponents.host = "api.playbattlegrounds.com"
    urlComponents.path = "/shards/\(regionShard.rawValue)/players"
    let playerNameItem = URLQueryItem(name: "filter[playerNames]", value: "\(name)")
    urlComponents.queryItems = [playerNameItem]
    guard let url = urlComponents.url else { fatalError("Could not create URL from components") }
    print(url)

    var request = URLRequest(url: url)
    request.httpMethod = "GET"
    request.setValue("bearer \(apiKey)", forHTTPHeaderField: "Authorization")
    request.setValue("application/vnd.api+json", forHTTPHeaderField: "Accept")

    let config = URLSessionConfiguration.default
    let session = URLSession(configuration: config)
    let task = session.dataTask(with: request) { (responseData, response, responseError) in
        DispatchQueue.main.async {
            if let error = responseError {
                completion?(.failure(error))
            } else if let jsonData = responseData {
                let decoder = JSONDecoder()

                do {
                    let players = try decoder.decode([Player].self, from: jsonData)
                    completion?(.success(players))
                } catch {
                    completion?(.failure(error))
                }
            } else {
                let error = NSError(domain: "", code: 0, userInfo: [NSLocalizedDescriptionKey : "Data was not retrieved from request"]) as Error
                completion?(.failure(error))
            }
        }
    }

    task.resume()
}

我面臨的問題是，當我嘗試運行網絡請求時出現此錯誤：

我認為我的可編碼結構有問題，但是我不確定。 有人可以指出正確的方向來尋找我的錯誤嗎？

Answer 1

如我所見，您整個玩家的反應都來自關鍵data 。 而且，您直接使用Player編碼結構解析播放器信息，而不是使用PlayerResponse編碼結構中的data鍵來解析播放器信息。

要解決此問題，請將您的代碼更新為：

let players = try decoder.decode(PlayerResponse.self, from: jsonData)

希望這能解決您的問題。

Answer 2

我建議您從頭開始進行構建，因為JSONDecoder的錯誤（與任何編譯器一樣）隨着結構的參與而變得越來越糟。 讓我們看看我們能走多遠：

您的Match結構非常好聽：

public struct Match: Codable {
    let type: String
    let id: String

}

let decoder = JSONDecoder()
let mData = """
   {"type":"match","id":"3e2a197a-1453-4569-b35b-99e337dfabc5"}
   """.data(using:.utf8)!
let match = try! decoder.decode(Match.self, from:mData)

print(match)

這里沒有意外的問題。 縮短Matches您已經遇到了第一個錯誤，而不是意外的錯誤

public struct Matches: Codable {
    let data: [Match]
}

let mtchsData = """
    {
        "data": [
            {"type":"match","id":"3e2a197a-1453-4569-b35b-99e337dfabc5"},
            {"type":"match","id":"15f41d2f-9da2-4b95-95ca-b85e297e14b7"},
            {"type":"match","id":"a42c496c-ad92-4d3e-af1f-8eaa2e200c2b"}
            {"type":"match","id":"b6e33df5-4754-49da-9a0f-144842bfc306"},
            {"type":"match","id":"5b357cd1-35fe-4859-a2d7-48f263120bbd"}
        ]
    }
    """.data(using:.utf8)!
do {
    let mtches = try decoder.decode(Matches.self, from:mtchsData)
    print(mtches)
} catch {
    print(error)
}

將顯示以下錯誤：

"dataCorrupted(Swift.DecodingError.Context(codingPath: [],
debugDescription: "The given data was not valid JSON.", 
underlyingError: Optional(Error Domain=NSCocoaErrorDomain Code=3840
    "Badly formed array around character 233."
UserInfo={NSDebugDescription=Badly 
    formed array around character 233.})))\n"

這是一個小錯誤，您在data Array第3行上缺少逗號。 添加所有內容都可以順利進行，但是如果您的服務中出現這種情況，則必須先對其進行修復。

我想您已經知道了，並且知道了逐步構建結構的方法。 在頂層，您會注意到頂層結構超出了Player數組，實際上，這是一個Dictionary以"data"為唯一鍵，正如您在PlayerResponse正確建模的那樣，正如@AnkitJayaswal所指出的那樣。 那已經造成了兩個錯誤，這些是我很容易發現的錯誤，但是正如我在繼續構建測試之前所建議的那樣，您將知道“較低”級別可以正確解析，並且可以專注於該問題。手。

以上所有內容在Playground中均可輕松實現，並且無需在此過程中實際調用WebService。 當然，您將必須import Cocoa ，但是您已經知道這一點。 無論如何，通過將問題分解成更小的部分，它總是有助於降低復雜性。