Parsing JSON With Codable in Swift - json

Question

I am attempting to parse JSON with codable in Swift. I have successfully done this before, but I have a more complicated JSON object with some arrays and I am having trouble.
Here is my 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":{}
}
Here are the models I am using:
public struct PlayerResponse: Codable {
let data: [Player]
}
For Player:
public struct Player: Codable {
let type: String
let id: String
let attributes: Attributes
let relationships: Relationships
}
For Attributes:
public struct Attributes: Codable {
let name: String
let patchVersion: String
let shardId: String
let titleId: String
let updatedAt: String
}
For Relationships:
public struct Relationships: Codable {
let matches: Matches
}
For Matches:
public struct Matches: Codable {
let data: [Match]
}
For Match:
public struct Match: Codable {
let type: String
let id: String
}
Decoding as:
let players = try decoder.decode([Player].self, from: jsonData)
I have this function which runs my network request:
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()
}
The problem I am facing is that I get this error when I try to run the network request:
I think there is an issue with my codable structs, but I'm not sure. Could someone point me in the right direction to look for my error?

Answer 1

I suggest you build this up from the ground, since the errors of JSONDecoder (as with any compiler) get worse the more involved your structures are. Let's see how far we get:
Your Match struct is pretty sound:
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)
No unexpected problems here. Shortening Matches a bit you already get your first error, rather an unexpected one
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)
}
will print the following error:
"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"
This is a trivial error, you are missing a comma on line 3 of the data Array. Adding that all will go well, but if it comes like this from your service you will have to fix it first.
I guess you get the idea and know your way about building up the structure successively. On the top level you will notice that your top level structure goes beyond an array of Player, it is actually a Dictionary with "data" as its sole key as you modelled correctly in PlayerResponse as #AnkitJayaswal pointed out already. That makes two errors already, those are the ones I managed to spot easily, but as I suggested before you should continue the build up of tests, that way you will know that the "lower" levels parse correctly and can concentrate on the problem at hand.
All of the above works easily in a Playground and there is no need to actually call the WebService in the process. Of course you will have to import Cocoa, but you already knew that. Anyway it always helps to reduce the level of complexity by splitting up your problem into smaller parts.

Answer 2

As I can see your whole player response is in key data. And your parsing player info with Player codable struct directly rather than data key which is used in PlayerResponse codable struct.
To resolve this update your code as:
let players = try decoder.decode(PlayerResponse.self, from: jsonData)
Hope this will solve your problem.