Swift URLSession and Combine json array decode fails

Question

Well guys like the title says i have on a response service call an JSON array and i cant find the way to decode with Combine: URLSession.shared.dataTaskPublisher

Service Response: https://codebeautify.org/alleditor/y228809f7

My Request Code:

public func getGasStationDiscounts(requestModel: GasStationDiscountsRequestDomainModel) -> CiMAObservable<GasStationDiscountsDomainModel> {
    guard let url = URL(string: RepositoryConstants.baseURL + String(format: RepositoryConstants.EndPoints.gasStationDiscounts, requestModel.gasStationID)) else {
        return Fail(error: NSError(domain: "URL Invalid", code: 001, userInfo: nil)).eraseToAnyPublisher()
    }
    
    var urlRequest = URLRequest(url: url)
    urlRequest.httpMethod = "GET"
    urlRequest.addValue("application/json", forHTTPHeaderField: "Accept")
    urlRequest.addValue("application/json", forHTTPHeaderField: "Content-Type")
    
    return URLSession.shared.dataTaskPublisher(for: urlRequest)
        .map(\.data)
        .decode(type: GasStationDiscountsDataModel.self, decoder: JSONDecoder())
        .map { model -> GasStationDiscountsDomainModel in
            model.parseToDomainModel()
        }.eraseToAnyPublisher()
}

Decodable File: https://codebeautify.org/alleditor/y2296aefe

So resuming, my problem is on trying to decode it because its an Array, on my project i'm working with diferent layers like Data, Domain and the Presentation (don't ask about architecture cuz is a new one, CiMA on GitHub) its a Hybrid Viper arch.

Thanks in advance!

EDITED: SOLVED! So finally i found a Solution which don't destroy my architecture. So here the small changes on decodable Files: https://codebeautify.org/alleditor/y22ad811e

and the last changes on the Request:

    public func getGasStationDiscounts(requestModel: GasStationDiscountsRequestDomainModel) -> CiMAObservable<GasStationDiscountsDomainModel> {
    guard let url = URL(string: RepositoryConstants.baseURL + String(format: RepositoryConstants.EndPoints.gasStationDiscounts, requestModel.gasStationID)) else {
        return Fail(error: NSError(domain: "URL Invalid", code: 001, userInfo: nil)).eraseToAnyPublisher()
    }
    
    var urlRequest = URLRequest(url: url)
    urlRequest.httpMethod = "GET"
    urlRequest.addValue("application/json", forHTTPHeaderField: "Accept")
    urlRequest.addValue("application/json", forHTTPHeaderField: "Content-Type")
    
    return URLSession.shared.dataTaskPublisher(for: urlRequest)
        .map(\.data)
        .decode(type: [GasStationDiscountsDataModel].self, decoder: JSONDecoder())
        .map { model -> GasStationDiscountsDomainModel in
            let stationDiscountsDomainModel = model.map { model -> StationDiscountDomainModel in
                model.parseToDomainModel()
            }
            return GasStationDiscountsDomainModel(stationDiscounts: stationDiscountsDomainModel)
        }
        .mapError { error in
            print(error.localizedDescription)
            return error
        }.eraseToAnyPublisher()
}

Do not add a solution to the question. If you have a solution, put it in an answer. Question; answer. It's a pretty clear distinction. Answering your own question, and even accepting that answer, is totally legal. — matt
– matt, Commented Dec 31, 2022 at 1:56

burnsi · Accepted Answer · 2022-09-23 22:25:55Z

1

The response seems to be an array. There is no top level element. Use:

.decode(type: [StationDiscountDataModel].self, decoder: JSONDecoder())

answered Sep 23, 2022 at 22:25

burnsi

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5 Comments

coden0w Over a year ago

mmm still without working if you see my code i had a model.parseToDomainModel() and i need it because its working with different layers Data (repositories) Domain (Business)

burnsi Over a year ago

@coden0w What do you mean by "still without working". Your question was about decoding, was it? Decoding to an array of your structs works for me. And at least for me there seems pretty straight forward to map this to the desired output.

coden0w Over a year ago

i solved it at final, i will add the solution, in few minutes. thank you burnsi! (for the fast reply to my question :))

burnsi Over a year ago

@coden0w If this answer helped you solve your problem please consider marking it as the accepted answer (green checkmark).

coden0w Over a year ago

done! and yes helped me!

stosha · Accepted Answer · 2022-09-24 05:07:38Z

0

Create custom operator something like this:

 extension Publisher where Output == Data {
    func customOperator() -> AnyPublisher<GasStationDiscountsDataModel, Never>  {
       return Just(GasStationDiscountsDataModel(data: self as! Data))
              .eraseToAnyPublisher()
       }
 }

And then use it:

 return URLSession.shared.dataTaskPublisher(for: urlRequest)
    .map(\.data)
    .customOperator()
    .map { model -> GasStationDiscountsDomainModel in
        model.parseToDomainModel()
    }.eraseToAnyPublisher()

edited Sep 24, 2022 at 5:07

answered Sep 23, 2022 at 23:27

stosha

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