How to decode DynamicKeys & CodingKeys in the same container? - ios

Question

Consider the following JSON: I'm trying to decode the "teams" object.
let jsonString = """
{
"Superheroes":{
"Marvel":"107",
"DC":"106"
},
"teams":{
"106":{
"name":"Marvel",
"Superheroes":{
"890":{
"name":"Batman"
}
}
},
"107":{
"name":"DC",
"Superheroes":{
"891":{
"name":"Wonder Woman"
}
}
}
}
}
"""
I have tried something like this:
struct SuperheroResponse: Decodable {
let teams: [Team]
private enum CodingKeys: String, CodingKey {
case teams = "teams"
}
private struct DynamicCodingKeys: CodingKey {
var stringValue: String
init?(stringValue: String) {
self.stringValue = stringValue
}
var intValue: Int?
init?(intValue: Int) {
return nil
}
}
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
let teamContainer = try container.nestedContainer(keyedBy: CodingKeys.self, forKey: CodingKeys.teams)
print(teamContainer.allKeys.count)
let tempArray: [Team] = []
for key in teamContainer.allKeys {
let decodedObject = try teamContainer.decode(Team.self, forKey: DynamicCodingKeys(stringValue: key.stringValue)!)
tempArray.append(decodedObject)
}
teams = tempArray
}
}
struct Team: Decodable {
let name: String
}
I thought that first I would get the teams container, map over the keys and go on from there. Problem is teamContainer.allKeys.count is always zero.
Also the following line, results in following error: Cannot convert value of type 'SuperheroResponse.DynamicCodingKeys' to expected argument type 'SuperheroResponse.CodingKeys'
let decodedObject = try teamContainer.decode(Team.self, forKey: DynamicCodingKeys(stringValue: key.stringValue)!)
Finally I decode it as follows:
let jsonData = Data(jsonString.utf8)
let decodedResult = try! JSONDecoder().decode(SuperheroResponse.self, from: jsonData)
dump(decodedResult)
Any help would be appreciated. Ideally I would like something like SuperheroResponse -> [Team],
Team -> name, [Superhero], Superhero -> name

Answer 1

You just have a couple of minor mistakes. You're almost there.
The team container is keyed by DynamicCodingKeys:
let teamContainer = try container.nestedContainer(keyedBy: DynamicCodingKeys.self, // <=
forKey: .teams)
And the Teams can be decoded as using the key you're given:
let decodedObject = try teamContainer.decode(Team.self, forKey: key)
Also, tempArray needs to be var:
var tempArray: [Team] = []
Or replace that loop with a map:
teams = try teamContainer.allKeys.map {
try teamContainer.decode(Team.self, forKey: $0)
}
All together:
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
let teamContainer = try container.nestedContainer(keyedBy: DynamicCodingKeys.self, forKey: .teams)
teams = try teamContainer.allKeys.map {
try teamContainer.decode(Team.self, forKey: $0)
}
}