Parsing JSON using codable and ignoring first layer of JSON - json

Question

I have JSON like this:
{
"success": true,
"message": "",
"result": {
"buy": [
{
"Quantity": 0.0056,
"Rate": 18527
},
{
"Quantity": 0.11431426,
"Rate": 18526
}
],
"sell":[
{
"Quantity": 8.20604116,
"Rate": 18540
},
{
"Quantity": 0.95600491,
"Rate": 18574.99999998
}
]
}
}
and another set of JSON like this:
{
"lastUpdateId": 1027024,
"bids": [
[
"4.00000000", // PRICE
"431.00000000", // QTY
[] // Can be ignored
]
],
"asks": [
[
"4.00000200",
"12.00000000",
[]
]
]
}
What is the best way to parse these two responses using codable. They both need to be parsed using the same struct or need to be converted to the same struct (whatever will do the job faster). I don't want to create a struct for the entire first response because I am not going to use keys like "success" and "message". I basically want to ignore those and get directly to the "result" key But in the second response, I will being using all the data so I have created a struct for that called TotalOrderBook. What is the best way to do this?
What is confusing me is ignoring the keys "success" and "message" in the first JSON response and getting straight to the value for the key "result". Is it possible to do that without creating an additional struct?
This is what I have right now. I would like to avoid adding another struct since the only thing I really need is the values under buy/bid and sell/sell.
struct TotalOrderBook:Codable{
var buy:[UniversalOrder]?
var sell:[UniversalOrder]?
var bid:[UniversalOrder]?
var ask:[UniversalOrder]?
var buyOrderBook: [UniversalOrder] {
return bid ?? buy ?? [UniversalOrder]()
}
var sellOrderBook: [UniversalOrder] {
return ask ?? sell ?? [UniversalOrder]()
}
var updatedTime:Date
}
struct UniversalOrder:Codable{
var price : Double {
return Double(rate ?? binPrice ?? 0)
}
var size : Double {
return Double(quantity ?? binQuantity ?? 0 )
}
//let numOrders : Int
var quantity:Double?
var rate:Double?
var binPrice:Double?
var binQuantity:Double?
private enum CodingKeys: String, CodingKey {
case rate = "Rate"
case quantity = "Quantity"
//case numOrders, binPrice,
}
init(from decoder: Decoder) throws {
var container = try decoder.unkeyedContainer()
binPrice = Double(try container.decode(String.self)) ?? nil
binQuantity = Double(try container.decode(String.self)) ?? nil
quantity = nil
rate = nil
}
}
This is how I am decoding:
let decoder = JSONDecoder()
let data = try! JSONSerialization.data(withJSONObject: value) //value is the response from Alamofire
var theWholeOrderBook:UniversalOrder!
do {
theWholeOrderBook = try decoder.decode(UniversalOrder.self, from: data)
} catch let error {
//print ("error is \(e) ** \(value)")
}

Answer 1

To answer your questions directly, yes it is very easy to ignore the success and message key-value pairs and head straight to results.
Despite this it will be a bit complicated to have a single struct to parse both of these JSON responses.
Both of them have a very different structure which will make it easier to use two different structs to use encoding. To highlight some differences :
buy, sell are nested inside results. bids, asks aren't.
The keys are completely different.
buy, sell have an array of key-value pairs while bids, asks simple have an array of values.
Codable structs should be simple and clear. It's better to have two of those corresponding to each response.