How to extract data from nested JSON with Swift 4 with dynamic keys

Question

I have a JSON data structure using unique keys that are created on upload. I can read all of it if I read each dictionary item line by line. However, I\'m trying to modify m

Answer 1

You can get keys from your current json as

 jq -r 'keys[]'

After that query in the loop by each key retrieved

Answer 2

You can try something like this:

let data = jsonData.data(using: .utf8)
let json = try JSONSerialization.jsonObject(with: data!) as! [String:Any]
let things = json["things"] as! [String:Any]

for (thing_key, thing_value)   in things as [String:Any] {

    let thing = thing_value as! [String:Any]
    if let cases = thing["cases"] as? [String:Any]{
        for (case_key, case_value) in cases {
            print(case_key)
            print(case_value)
        }
    }
}

EDIT I initially missunderstood your question , here is your code improved to obtain the cases. It was a quick job so might not be optimal, but you get the idea:

struct Thing: Decodable {
    let id: String
    let isActive: Bool
    let name: String
    let owner: String
    var cases: [Case]?

    init(id: String, isActive: Bool, name: String, owner: String , cases: [Case]?) {
        self.id = id
        self.isActive = isActive
        self.name = name
        self.owner = owner
        self.cases = cases

    }
}
struct User: Decodable {
    let id: String
    let name: String
}
struct Case: Decodable {
    let id: String
    let caseNumber: Int
}
struct ResponseData: Decodable {
    var things = [Thing]()
    var users = [User]()


    enum CodingKeys: String, CodingKey {
        case things
        case users
        case cases
    }

    private struct PhantomKeys: CodingKey {
        var intValue: Int?
        var stringValue: String
        init?(intValue: Int) { self.intValue = intValue; self.stringValue = "\(intValue)" }
        init?(stringValue: String) { self.stringValue = stringValue }
    }

    private enum ThingKeys: String, CodingKey {
        case isActive, name, owner, cases
    }
    private enum UserKeys: String, CodingKey {
        case name
    }
    private enum CaseKeys: String, CodingKey {

        case no
    }

    init(from decoder: Decoder) throws {

        let outer = try decoder.container(keyedBy: CodingKeys.self)
        let thingcontainer = try outer.nestedContainer(keyedBy: PhantomKeys.self, forKey: .things)

        for key in thingcontainer.allKeys {
            let aux = try thingcontainer.nestedContainer(keyedBy: ThingKeys.self, forKey: key)

            let name = try aux.decode(String.self, forKey: .name)
            let owner = try aux.decode(String.self, forKey: .owner)
            let isActive = try aux.decode(Bool.self, forKey: .isActive)


            var cases:[Case]? = []
            do{
                let casescontainer = try aux.nestedContainer(keyedBy: PhantomKeys.self, forKey: .cases)
                    for case_key in casescontainer.allKeys{

                        let caseaux = try casescontainer.nestedContainer(keyedBy: CaseKeys.self, forKey: case_key)
                        let no = try caseaux.decode(Int.self, forKey: .no)
                        let thingCase = Case(id:case_key.stringValue, caseNumber: no)
                        cases?.append(thingCase)
                }

            }catch{ }


            let thing = Thing(id: key.stringValue, isActive: isActive, name: name, owner: owner , cases: cases)
            things.append(thing)
        }
        let usercontainer = try outer.nestedContainer(keyedBy: PhantomKeys.self, forKey: .users)

        for key in usercontainer.allKeys {
            let aux = try usercontainer.nestedContainer(keyedBy: UserKeys.self, forKey: key)
            let name = try aux.decode(String.self, forKey: .name)
            let user = User(id: key.stringValue,name: name)
            users.append(user)
        }
    }
}

This produce this output:

let data = json.data(using: .utf8)!
let things = try JSONDecoder().decode(ResponseData.self, from: data).things
print("-----")
for thing in things{
    print(thing)
}
print("---")
let users = try JSONDecoder().decode(ResponseData.self, from: data).users
for user in users{
    print(user)
}

---

-----
Thing(id: "456", isActive: true, name: "Bus", owner: "Joe", cases: Optional([]))
Thing(id: "123", isActive: true, name: "Party", owner: "Bob", cases: Optional([__lldb_expr_283.Case(id: "case1", caseNumber: 1), __lldb_expr_283.Case(id: "case2", caseNumber: 2)]))
---
User(id: "u1", name: "Summer")
User(id: "u2", name: "Daffy")