POST method in Swift4 urlSession Decodable not working(What goes wrong here?) - swift4

Question

I am trying to post 2 parameters (email: and password) to get a response from the server with detailed user information, I build API to handle this and get a good response using Postman, but when I tried to implement this with Swift4 new urlsession JSON decode and encode, it keeps failing and I got error on decoding the response data.
this my JSON response when using Postman:
{
"error": "false",
"message": "downloaded",
"UserInfo": {
"id": 5,
"email": "abc#hotmail.com",
"lastname": "Bence",
"name": "Mark",
"phone": "1234567",
"add1": "333",
"add2": "444",
"city": "ott",
"postalcode": "tttttt"
}
}
My struct file:
import UIKit
struct loginPost: Encodable {
let email: String
let password: String
}
struct User: Decodable {
let error: String?
let message: String?
let UserInfo: [UserData]
}
struct UserData: Codable {
let id: Int?
let email: String?
let lastname: String?
let name: String?
let phone: String?
let add1: String?
let add2: String?
let city: String
let postalcode: String?
}
My Function
func downloadJson() {
let url = URL(string: http://192.168.0.10/api/login_hashed.php)
guard let downloadURL = url else { return }
//POST Req
var request = URLRequest(url: downloadURL)
request.httpMethod = "POST"
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.addValue("application/json", forHTTPHeaderField: "Accept")
let newpost = loginPost(email: "abc#hotmail.com", password: "123456")
do {
let jsonBody = try JSONEncoder().encode(newpost)
request.httpBody = jsonBody
print(jsonBody)
}catch{
print("some error")
}
URLSession.shared.dataTask(with: request) { data, urlResponse, error in
guard let data = data, error == nil, urlResponse != nil else {
print("something is wrong with url")
return
}
print("downloaded..")
do
{
let decoder = JSONDecoder()
let downloaduser = try decoder.decode(User.self, from: data)
self.logmessage = downloaduser.message!
print(self.logmessage)
DispatchQueue.main.async {
// self.tableView.reloadData()
}
} catch {
print("something wrong with decode")
}
}.resume()
}

Answer 1

I have figured it out finally, thanks,.
I just want to mention the cause of this error and share my experience.
The main cause is the way you send JSON and receive the incoming response. you should know exactly how the data look in order to create your struct the acceptable way.
My return data is just simple 2 line of text and array of text, my struct was:
import UIKit
struct loginPost: Encodable {
let email: String
let password: String
}
struct User: Decodable {
let error: String?
let message: String?
let UserInfo: [UserData]
}
struct UserData: Codable {
let id: Int?
let email: String?
let lastname: String?
let name: String?
let phone: String?
let add1: String?
let add2: String?
let city: String
let postalcode: String?
}
my mistake on line 18
let UserInfo: [UserData]
it should be
let UserInfo: UserData?
without the square bracket.
one more important point, always try to catch the decode error and it's dicription by implementing }catch let JsonErr {, it will give you exactly why the decode not working.
in my case:
downloaded.. something wrong after downloaded
typeMismatch(Swift.Array, Swift.DecodingError.Context(codingPath:
[h2h.User.(CodingKeys in _E33F61CC43E102744E4EF1B7E9D7EDDE).UserInfo],
debugDescription: "Expected to decode Array but found a
dictionary instead.", underlyingError: nil))
And make sure to make your server API to accept JSON format application/json and
decode what you send in order to receive what you looking for;
php code service API
$UserData = json_decode(file_get_contents("php://input"), true);

Answer 2

Simplest and easy way to decode the json.
MUST TRY
struct Welcome: Codable {
let error, message: String?
let userInfo: UserInfo?
enum CodingKeys: String, CodingKey {
case error, message
case userInfo = "UserInfo"
}
}
// MARK: - UserInfo
struct UserInfo: Codable {
let id: Int?
let email, lastname, name, phone: String?
let add1, add2, city, postalcode: String?
}
After that in your code , when you get response from api then write
let decoder = JSONDecoder()
let obj = try! decoder.decode(Welcome.self, from: jsonData!)
Print(obj)

Answer 3

List item
This Will work Are You Creating Model Is Wrong
struct loginPost: Encodable {
let email: String
let password: String
}
struct Users:Codable {
var error:String?
var message:String?
var UserInfo:UserDetails?
}
struct UserDetails:Codable {
let id: Int?
let email: String?
let lastname: String?
let name: String?
let phone: String?
let add1: String?
let add2: String?
let city: String
let postalcode: String?
}
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
downloadJson()
}
func downloadJson() {
let url = URL(string: "http://192.168.0.10/api/login_hashed.php")
guard let downloadURL = url else { return }
//POST Req
var request = URLRequest(url: downloadURL)
request.httpMethod = "POST"
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.addValue("application/json", forHTTPHeaderField: "Accept")
let newpost = loginPost(email: "abc#hotmail.com", password: "123456")
do {
let jsonBody = try JSONEncoder().encode(newpost)
request.httpBody = jsonBody
print(jsonBody)
}catch{
print("some error")
}
URLSession.shared.dataTask(with: request) { data, urlResponse, error in
guard let data = data, error == nil, urlResponse != nil else {
print("something is wrong with url")
return
}
print("downloaded..")
do
{
let decoder = JSONDecoder()
let downloaduser = try decoder.decode(Users.self, from: data)
// self.logmessage = downloaduser.message!
// print(self.logmessage)
DispatchQueue.main.async {
// self.tableView.reloadData()
}
} catch {
print("something wrong with decode")
}
}.resume()
}
}