Xamarin JSON Deserialize - json

Question

I created a HTTPWebRequest to check if the username and password of the user is correct. If the username and password of the user is correct it will return a JSON Array with the ContactID of the user. I tried to deserialize the JSON but I failed to get the actual data. I want to get the Contact id and send the data to a variable of the next page.
The output of the JSON when the username and password is correct:
[{"ContactID":"1"}]
My code:
using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.IO;
using System.Net;
using System.Text;
using System.Windows.Input;
using TBSMobileApplication.Data;
using TBSMobileApplication.View;
using Xamarin.Essentials;
using Xamarin.Forms;
namespace TBSMobileApplication.ViewModel
{
public class LoginPageViewModel : INotifyPropertyChanged
{
void OnProperyChanged(string PropertyName)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(PropertyName));
}
public string username;
public string password;
public string Username
{
get { return username; }
set
{
username = value;
OnProperyChanged(nameof(Username));
}
}
public string Password
{
get { return password; }
set
{
password = value;
OnProperyChanged(nameof(Password));
}
}
public ICommand LoginCommand { get; set; }
public LoginPageViewModel()
{
LoginCommand = new Command(OnLogin);
}
public void OnLogin()
{
if (string.IsNullOrEmpty(Username) || string.IsNullOrEmpty(Password))
{
MessagingCenter.Send(this, "Login Alert", Username);
}
else
{
var current = Connectivity.NetworkAccess;
if (current == NetworkAccess.Internet)
{
var link = "http://192.168.1.25:7777/TBS/test.php?User=" + Username + "&Password=" + Password;
var request = HttpWebRequest.Create(string.Format(#link));
request.ContentType = "application/json";
request.Method = "GET";
using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
{
if (response.StatusCode != HttpStatusCode.OK)
{
Console.Out.WriteLine("Error fetching data. Server returned status code: {0}", response.StatusCode);
}
else
{
using (StreamReader reader = new StreamReader(response.GetResponseStream()))
{
var content = reader.ReadToEnd();
if (content.Equals("[]") || string.IsNullOrWhiteSpace(content) || string.IsNullOrEmpty(content))
{
MessagingCenter.Send(this, "Http", Username);
}
else
{
var usr = JsonConvert.DeserializeObject(content);
App.Current.MainPage.Navigation.PushAsync(new DatabaseSyncPage(), true);
}
}
}
}
}
else
{
MessagingCenter.Send(this, "Not Connected", Username);
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
}
}

Answer 1

Modify your code else block like below
if (content.Equals("[]") || string.IsNullOrWhiteSpace(content) || string.IsNullOrEmpty(content))
{
MessagingCenter.Send(this, "Http", Username);
}
else
{
var response = JsonConvert.DeserializeObject<List<LoggedInUser>>(content);
var contactId=response[0].ContactID;
//response have your ContactID value. Try to debug & see.
App.Current.MainPage.Navigation.PushAsync(new DatabaseSyncPage(), true);
}
Create one another public class to deserialize your response
public class LoggedInUser
{
public string ContactID { get; set; }
}
If you have more than 1 record in result(as you asked this in comment below)
you can get them using loops
for (int i = 0; i < response.Count; i++)
{
var item = response[i];
var contactId = item.ContactId;
}
Hope it help you.

Answer 2

JSON Response object is not looking standard format for output result. Whatever for JSON deserialization you should create separate class as per below code.
public class RootObject
{
public string ContactID { get; set; }
}
Public Void ServiceRequest()
{
var content = reader.ReadToEnd();
if(!String.IsNullOrEmpty(content)
{
var response = JsonConvert.DeserializeObject<RootObject>(content);
}
}
I hope it will be useful.