Decoding an API response in Swift

Question

I'm using Alamofire to decode objects, and my JSON looks like this

{
  "wallet": {
    "public_key": "ADDRESS",
    "name": "My test wallet",
    "id": "-MQ9NdAyMaK3WQfSOYZW",
    "owner": "Kca8BNHy8FemIxPO7FWBSLE8XKN2",
    "currency": "ME",
    "metadata": {
      "legacy_address": "WHAT",
      "x_pub_address": "SOMETHING COOL"
    }
  },
  "secrets": {
    "wif": "SOMETHING",
    "private_key": "SOMETHING ELSE",
    "mnemonic": "YOU WISH"
  }
}

My Swift looks like this:

class Response: Codable {

   var wallet: Wallet
   var secrets: [String: String]
}

class Wallet: Codable {
   var publicKey: String
   var name: String
   var id: String
   var owner: String
   var currency: String
   var metadata: [String: String]

   enum WalletKeys: String, CodingKey{
      case publicKey = "public_key",
      case name, 
      case id 
      case owner, 
      case currency,
      case metadata
   }
}

I'm getting a keyNotFound(CodingKeys(stringValue: "publicKey")) error, and I dont know why. Can someone help me figure this out?

you have to add all your variable on enum WalletKeys: String, CodingKey, check this https://stackoverflow.com/questions/44396500/how-do-i-use-custom-keys-with-swift-4s-decodable-protocol — cristian_064, Jan 08 '21 at 03:27
case publicKey = "public_key" case name, id owner, currency, metadata , please read the link. — cristian_064, Jan 08 '21 at 03:39
Yeah @luffy_064 I read the link, updated my Swift file above and in my code, still getting the same issue — Randomuser123, Jan 08 '21 at 03:41
It is painful to hardcode constructs to map the json structure. You should try https://app.quicktype.io/. — Stephen Chen, Jan 08 '21 at 03:54

Leo Dabus · Accepted Answer · 2021-01-08T03:44:53.837

You need to set your decoder keyDecodingStrategy property value to .convertFromSnakeCase:

struct Response: Codable {
    let wallet: Wallet
    let secrets: Secrets
}

struct Secrets: Codable {
    let wif: String
    let privateKey: String
    let mnemonic: String
}

struct Wallet: Codable {
    let publicKey: String
    let name: String
    let id: String
    let owner: String
    let currency: String
    let metadata: Metadata
}

struct Metadata: Codable {
    let legacyAddress: String
    let xPubAddress: String
}

let json = """
{
  "wallet": {
    "public_key": "ADDRESS",
    "name": "My test wallet",
    "id": "-MQ9NdAyMaK3WQfSOYZW",
    "owner": "Kca8BNHy8FemIxPO7FWBSLE8XKN2",
    "currency": "ME",
    "metadata": {
      "legacy_address": "WHAT",
      "x_pub_address": "SOMETHING COOL"
    }
  },
  "secrets": {
    "wif": "SOMETHING",
    "private_key": "SOMETHING ELSE",
    "mnemonic": "YOU WISH"
  }
}
"""

do {
    let decoder = JSONDecoder()
    decoder.keyDecodingStrategy = .convertFromSnakeCase
    let root = try decoder.decode(Response.self, from: Data(json.utf8))
    print(root)
} catch {
    print(error)
}

This will print:

Response(wallet: Wallet(publicKey: "ADDRESS", name: "My test wallet", id: "-MQ9NdAyMaK3WQfSOYZW", owner: "Kca8BNHy8FemIxPO7FWBSLE8XKN2", currency: "ME", metadata: Metadata(legacyAddress: "WHAT", xPubAddress: "SOMETHING COOL")), secrets: __lldb_expr_1.Secrets(wif: "SOMETHING", privateKey: "SOMETHING ELSE", mnemonic: "YOU WISH"))

Tried this, getting the same error. Also this shouldn't be the case anyway because I set custom coding keys. — Randomuser123, Jan 08 '21 at 03:39
@Randomuser123 it should be called CodingKeys. I will edit my post — Leo Dabus, Jan 08 '21 at 03:41
Yup this worked, also another easier & shorter fix was just setting the enum to be of type `CodingKeys` :)) — Randomuser123, Jan 08 '21 at 03:48
I usually prefer setting the property. Just personal preference. — Leo Dabus, Jan 08 '21 at 03:51

Decoding an API response in Swift

1 Answers1