Xamarin MVVM passing data to other view - xamarin

Question

I want to pass the data to another view page. So far I can get the data I need to pass. My problem is how do I pass the data in MVVM. I used Application.Current.MainPage.Navigation.PushAsync(new DatabaseSyncPage(), true); When I add contactId inside DatabaseSyncPage() an error occurs. "The error is 'DatabaseSyncPage' does not contain a constructor that takes 1 arguments"
My code:
LoginPageViewModel.cs
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 class LoggedInUser
{
public string ContactID { get; set; }
}
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 result = JsonConvert.DeserializeObject<List<LoggedInUser>>(content);
var contactId = result[0].ContactID;
Application.Current.MainPage.Navigation.PushAsync(new DatabaseSyncPage { myId = contactId }, true);
}
}
}
}
else
{
MessagingCenter.Send(this, "Not Connected", Username);
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
}
}
DatabaseSyncPage.xaml.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;
namespace TBSMobileApplication.View
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class DatabaseSyncPage : ContentPage
{
public int myId { get; set; }
public DatabaseSyncPage ()
{
InitializeComponent ();
DisplayAlert("Message", Convert.ToString(myId), "ok");
}
}
}

Answer 1

If you want to send the int. First declare that in your DatabaseSyncPage
Like below
public partial class DatabaseSyncPage : ContentPage
{
public DatabaseSyncPage( int Id)
{
}
}
& when you are pushing your page in your code else block do like this
if (content.Equals("[]") || string.IsNullOrWhiteSpace(content) || string.IsNullOrEmpty(content))
{
MessagingCenter.Send(this, "Http", Username);
}
else
{
var result = JsonConvert.DeserializeObject<List<LoggedInUser>>(content);
var contactId = result[0].ContactID;
Application.Current.MainPage.Navigation.PushAsync(new DatabaseSyncPage(contactId), true);
}

Answer 2

I'm assuming that contactID is an int.
Create an additional constructor in your DatabaseSyncPage:
public DatabaseSyncPage (int contactID)
{
// TODO: Do something with your id
}
But this passes the data to the page, not the page model.
Are you using any kind of framework? It would probably be worth looking into that.

Answer 3

You can use xamrin.plugins.settings nuget package.