swift 4 - json decode object with tree structure - json

Question

I want to decode my user json object, but I have my difficulties with decoding the superior object. The superior object is just another user that stands above the user. The structure looks like this
{
"id": 3,
"username": "a",
"email": "a#abc.com",
"userFunction": "4",
"password": "****",
"superior": {
"id": 2,
"username": "b",
"email": "b#abc.com",
"userFunction": "3",
"password": "****",
"superior": {
"id": 1,
"username": "c",
"email": "c#abc.com",
"userFunction": "1",
"password": "****",
"superior": null,
},
},
}
struct UserStructure: Decodable {
var id: Int64?
var username: String?
var email: String?
var userFunction: UserFunctionStructure?
var password: String?
var superior: UserStructure?
}
func fetchUser(username: String){
let urlString = "http://localhost:8080/rest/user/" + username
let url = URL(string: urlString)!
URLSession.shared.dataTask(with: url) { (data, response, error) -> Void in
if error != nil {
print(error!)
return
}
guard let data = data else {
return
}
do {
let user = try JSONDecoder().decode(UserStructure.self, from: data)
print(user)
} catch let err {
print(err)
}
}.resume()
}
When I set the type of superior to "UserStructure?" I get the error "Value Type 'UserStructure" cannot have a stored property that recursively contains it. I thought about creating a SuperiorStructure but then I would have the same problem a step further.

Answer 1

Like the compiler error message says, structs cannot have properties that contain an instance of themselves. Use class in this case:
class UserStructure: Decodable {
var id: Int64?
var username: String?
var email: String?
var userFunction: UserFunctionStructure?
var password: String?
var superior: UserStructure?
}