Problem with localID and preferences

Eduardo Gomez 3,416 Reputation points
2022-01-20T19:34:46.403+00:00

Hello

I have a tiny little problem.

In my App, I have a login method, that set the UserID into preferences

       public async Task LoginAsync(User users) {

            try {
                UserDialogs.Instance.ShowLoading(AppResources.Loading);
                var auth = await AuthProvider.SignInWithEmailAndPasswordAsync(users.Email, users.Password);
                var content = await auth.GetFreshAuthAsync();
                var serializedcontnet = JsonConvert.SerializeObject(content);
                App.UserID = auth.User.LocalId;
                Preferences.Set(App.UserID, App.UserID);
                Preferences.Set(App.FirebaseRefreshToken, serializedcontnet);
                UserDialogs.Instance.HideLoading();
                Application.Current.MainPage = new NavigationPage(new MainPage());
            } catch (FirebaseAuthException ex) {
                Firebasemessages.GetMessages(ex);
            }
            UserDialogs.Instance.HideLoading();

When I start the app again, I do something like

  public App() {

            SyncfusionLicenseProvider.RegisterLicense(KEY);

            InitializeComponent();

            var UserId = Preferences.Get(UserID, string.Empty);

            if (!string.IsNullOrEmpty(UserId)) {
                MainPage = new NavigationPage(new MainPage());
            } else {
                MainPage = new NavigationPage(new LoginPage());
            }
        }

So I am checking if I do not have a user ID, but when I log in, I save the UserID into Preferences, So it shouldn't ask again

Project

DuoNotes

Xamarin
Xamarin
A Microsoft open-source app platform for building Android and iOS apps with .NET and C#.
5,287 questions
{count} votes

Accepted answer
  1. Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 25,586 Reputation points Microsoft Vendor
    2022-01-21T02:27:01.66+00:00

    Hello,

    Welcome to our Microsoft Q&A platform!

    This Preferences.Set(App.UserID, App.UserID); method means you save a value( App.UserID ) for a given key( App.UserID ) in preferences.

    When you get the UserId ( var UserId = Preferences.Get(UserID, string.Empty); ) , the key is " UserID "( public static string UserID = "UserID"; ) . When you set the UserID into preferences, you set App.UserID = auth.User.LocalId;, the key is the value of auth.User.LocalId not " UserID ", so the value is null.
    You could replace the following code

     App.UserID = auth.User.LocalId;  
    Preferences.Set(App.UserID, App.UserID);  
    

    to

    App.UserID = auth.User.LocalId;  
    Preferences.Set("UserID", App.UserID);  
    

    or to

       // App.UserID = auth.User.LocalId;  
        Preferences.Set(App.UserID, auth.User.LocalId);  
    

    Best Regards,
    Wenyan Zhang


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