Empty List from JSON in SwiftUI - json

Question

I'm having some trouble fetching data from the PiHole API;
This is the JSON format (from the url http://pi.hole/admin/api.php?summary):
{
"domains_being_blocked": "1,089,374",
"dns_queries_today": "34,769",
"ads_blocked_today": "11,258",
"ads_percentage_today": "32.4",
"unique_domains": "9,407",
"queries_forwarded": "17,972",
"queries_cached": "5,539",
"clients_ever_seen": "35",
"unique_clients": "23",
"dns_queries_all_types": "34,769",
"reply_NODATA": "1,252",
"reply_NXDOMAIN": "625",
"reply_CNAME": "10,907",
"reply_IP": "21,004",
"privacy_level": "0",
"status": "enabled",
"gravity_last_updated": {
"file_exists": true,
"absolute": 1588474361,
"relative": {
"days": "0",
"hours": "14",
"minutes": "18"
}
}
}
This is my code:
ContentView.swift
import SwiftUI
struct NetworkController {
static func fetchData(completion: #escaping (([PiHole.Stat]) -> Void)) {
if let url = URL(string: "http://pi.hole/admin/api.php?summary") {
URLSession.shared.dataTask(with: url) { (data, response, error) in
if let data = data {
let stat = try? JSONDecoder().decode(PiHole.self, from: data)
completion(stat?.stats ?? [])
}
}.resume()
}
}
}
class ContentViewModel: ObservableObject {
#Published var messages: [PiHole.Stat] = []
func fetchData() {
NetworkController.fetchData { messages in
DispatchQueue.main.async {
self.messages = messages
}
}
}
}
struct ContentView: View {
#ObservedObject var viewModel = ContentViewModel()
var body: some View {
List {
ForEach(viewModel.messages, id: \.self) { stat in
Text(stat.domains_being_blocked)
}
}.onAppear{
self.viewModel.fetchData()
}
}
}
Data.swift
struct PiHole: Decodable {
var stats: [Stat]
struct Stat: Decodable, Hashable {
var domains_being_blocked: String
var ads_percentage_today: String
var ads_blocked_today: String
var dns_queries_today: String
}
}
Everything seems okay, no errors, yet when I run it, the simulator only shows an empty list
In Playground I can retrieve those data just fine:
import SwiftUI
struct PiHoleTest: Codable {
let domains_being_blocked: String
let ads_blocked_today: String
}
let data = try! Data.init(contentsOf: URL.init(string: "http://pi.hole/admin/api.php?summary")!)
do {
let decoder: JSONDecoder = JSONDecoder.init()
let user: PiHoleTest = try decoder.decode(PiHoleTest.self, from: data)
print("In Blocklist \(user.domains_being_blocked)")
print("Blocked Today: \(user.ads_blocked_today) ")
} catch let e {
print(e)
}
The Output:
In Blocklist 1,089,374
Blocked Today: 11,258
What am I doing wrong? Or better, is there another way to fetch these stats?
Thanks in Advance!

Answer 1

The issue was related to the structure. Your JSON decoded were not an array. So PiHole struct was unnecessary. I can tested and this code is working now.
import SwiftUI
struct NetworkController {
static func fetchData(completion: #escaping ((Stat) -> Void)) {
if let url = URL(string: "http://pi.hole/admin/api.php?summary") {
let request = URLRequest(url: url)
URLSession.shared.dataTask(with: request) { (data, response, error) in
do {
if let data = data {
let stat = try JSONDecoder().decode(Stat.self, from: data)
DispatchQueue.main.async() {
completion(stat)
}
return
} else {
print("Error Found")
}
} catch let error as NSError {
print(error.localizedDescription)
}
}.resume()
}
}
}
class ContentViewModel: ObservableObject {
#Published var stat: Stat? = nil
func fetchData() {
NetworkController.fetchData { stat in
self.stat = stat
}
}
}
struct TestView: View {
#ObservedObject var viewModel = ContentViewModel()
var body: some View {
List {
Text(viewModel.stat?.domains_being_blocked ?? "No Data")
Text(viewModel.stat?.ads_blocked_today ?? "No Data")
Text(viewModel.stat?.ads_percentage_today ?? "No Data")
Text(viewModel.stat?.dns_queries_today ?? "No Data")
}.onAppear{
self.viewModel.fetchData()
}
}
}
struct Stat: Decodable, Hashable {
var domains_being_blocked: String
var ads_percentage_today: String
var ads_blocked_today: String
var dns_queries_today: String
}