Parsing Nested JSON in SWIFT 4

Question

I am currently parsing JSON with Decodable in SWIFT 4.

The JSON is formatted as follows:

  {
  "autopayout_from": "1.010",
  "earning_24_hours": "9.74731104",
  "error": false,
  "immature_earning": 0.635593030875,
  "last_payment_amount": "1.91238210",
  "last_payment_date": "Mon, 26 Feb 2018 15:08:02 GMT",
  "last_share_date": "Mon, 26 Feb 2018 16:16:01 GMT",
  "payout_daily": false,
  "payout_request": false,
  "total_hashrate": 109006.86,
  "total_hashrate_calculated": 143855.75,
  "transferring_to_balance": 0.2281390807,
  "wallet": "0xbb76fc2ce36a19da28fd713e350a42f1023e2f7f",
  "wallet_balance": "0.49556201",
  "workers": {
    "10003": {
      "alive": false,
      "hashrate": 0.0,
      "hashrate_below_threshold": false,
      "hashrate_calculated": 0.0,
      "last_submit": "Mon, 26 Feb 2018 13:23:16 GMT",
      "second_since_submit": 10612,
      "worker": "10003"
    },
    "100151": {
      "alive": false,
      "hashrate": 0.0,
      "hashrate_below_threshold": false,
      "hashrate_calculated": 0.0,
      "last_submit": "Mon, 26 Feb 2018 09:30:30 GMT",
      "second_since_submit": 24578,
      "worker": "100151"
    },
    "100205": {
      "alive": true,
      "hashrate": 19.28,
      "hashrate_below_threshold": true,
      "hashrate_calculated": 24.85,
      "last_submit": "Mon, 26 Feb 2018 16:12:02 GMT",
      "second_since_submit": 486,
      "worker": "100205"
    },

I am able to easily parse things such as last_payment_ammount or last_payment_date with my Struct:

struct ticker: Codable{
    let error: Bool
    let wallet: String
    let earning_24_hours: String
    let immature_earning: Double
    let last_payment_amount: String
    let last_payment_date: String
    let total_hashrate: Double
    let total_hashrate_calculated: Double
    let wallet_balance: String
}

What I am really struggling to get my head around is getting the nested stuff.

How can I get for example a list of workers using the "worker" variable for example to maybe put into an array. Or parse the hashrate value for one worker?

Many thanks

Answer 1

Here's how I would model this:

struct Ticker: Codable {
    let autopayoutFrom, earning24_Hours: String
    let error: Bool
    let immatureEarning: Double
    let lastPaymentAmount, lastPaymentDate, lastShareDate: String
    let payoutDaily, payoutRequest: Bool
    let totalHashrate, totalHashrateCalculated, transferringToBalance: Double
    let wallet, walletBalance: String
    let workers: [String: Worker]

    enum CodingKeys: String, CodingKey {
        case autopayoutFrom = "autopayout_from"
        case earning24_Hours = "earning_24_hours"
        case error
        case immatureEarning = "immature_earning"
        case lastPaymentAmount = "last_payment_amount"
        case lastPaymentDate = "last_payment_date"
        case lastShareDate = "last_share_date"
        case payoutDaily = "payout_daily"
        case payoutRequest = "payout_request"
        case totalHashrate = "total_hashrate"
        case totalHashrateCalculated = "total_hashrate_calculated"
        case transferringToBalance = "transferring_to_balance"
        case wallet
        case walletBalance = "wallet_balance"
        case workers
    }
}

struct Worker: Codable {
    let alive: Bool
    let hashrate: Double
    let hashrateBelowThreshold: Bool
    let hashrateCalculated: Double
    let lastSubmit: String
    let secondSinceSubmit: Int
    let worker: String

    enum CodingKeys: String, CodingKey {
        case alive, hashrate
        case hashrateBelowThreshold = "hashrate_below_threshold"
        case hashrateCalculated = "hashrate_calculated"
        case lastSubmit = "last_submit"
        case secondSinceSubmit = "second_since_submit"
        case worker
    }
}

// usage examples:

let ticker = try JSONDecoder().decode(Ticker.self, from: data)
let workerKeys = ticker.workers.keys // "10003", "100151", "100205"
let workers = ticker.workers.values  // all workers objects

let alive = workers.filter { $0.alive } // all workers where alive==true
let totalHashrate = alive.reduce(0.0) { $0 + $1.hashrateCalculated }