Decode json string to struct from response data in Swift - json

Question

I have a test server written in python which produces json output on single path: '/'
import json
from fastapi import FastAPI
from uvicorn import run
app = FastAPI()
#app.get('/')
def main():
return json.dumps([{
'name': 'ihor',
'age': 5
}])
if __name__ == '__main__':
run(app, host='0.0.0.0')
Then I have my iOS client in SwiftUI and trying to fetch a json from my server and decode it into struct.
Here's the code of api call and decoding:
import SwiftUI
class Network: ObservableObject {
#Published var users: [User] = []
func getUsers() {
let url = URL(string: "http://localhost:8000")
let urlRequest = URLRequest(url: url!)
let dataTask = URLSession.shared.dataTask(with: urlRequest) { (data, response, error) in
if let error = error {
print("Request error: ", error)
return
}
guard let response = response as? HTTPURLResponse else { return }
if response.statusCode == 200 {
guard let data = data else { return }
DispatchQueue.main.async {
do {
print(String(decoding: data, as: UTF8.self))
let decodedUsers = try JSONDecoder().decode([User].self, from: data)
self.users = decodedUsers
} catch let error {
print("Error decoding: ", error)
}
}
}
}
dataTask.resume()
}
}
struct User: Decodable {
var name: String
var age: Int
}
And it's called from simple content view
import SwiftUI
struct ContentView: View {
#EnvironmentObject var network: Network
var body: some View {
ScrollView {
Text("All users")
.font(.title).bold()
if network.users.count > 0 {
Text(network.users.first!.name)
}
}
.onAppear {
network.getUsers()
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView() .environmentObject(Network())
}
}
After all it's produces the next output:
"[{\"name\": \"ihor\", \"age\": 5}]" Error decoding: typeMismatch(Swift.Array<Any>, Swift.DecodingError.Context(codingPath: [], debugDescription: "Expected to decode Array<Any> but found a string/data instead.", underlyingError: nil))
Looks like JSONDecoder cannot handle input with escaped backslashes and quotes at the start and at the end.
Everything works fine once I remove first and last quotes and escaped backslashes:
do {
let rawJsonString = String(decoding: data, as: UTF8.self)
let lowerIndex = rawJsonString.index(rawJsonString.startIndex, offsetBy: 1)
let upperIndex = rawJsonString.index(rawJsonString.endIndex, offsetBy: -1)
let jsonString = rawJsonString[lowerIndex..<upperIndex].replacingOccurrences(of: "\\", with: "")
print(jsonString)
let decodedUsers = try JSONDecoder().decode([User].self, from: jsonString.data(using:.utf8)!)
self.users = decodedUsers
} catch let error {
print("Error decoding: ", error)
}
But it's pretty dirty solution and wouldn't work with nested json that have to be escaped with backslashes.
Is there a simple solution to parse JSON like this to struct?