Pasing data to viewModel contractor

Question

Since I need m data immediately, I decide to pass my class to the WelomePage Contractor

public partial class WelcomePageViewModel : BaseViewModel {

    DemyUser? loggedUser;

    public WelcomePageViewModel(DemyUser demyUser) {

        loggedUser = demyUser;
        GetShellItems(loggedUser.CurrentRole);
    }

 private async void CheckAuth() {
     var currentUserAsJson = await SecureStorage.GetAsync(Constants.LOGGED_USER);
     if(string.IsNullOrEmpty(currentUserAsJson)) {
         if(DeviceInfo.Platform == DevicePlatform.WinUI) {
             Shell.Current.Dispatcher.Dispatch(async () => {
                 await Shell.Current.GoToAsync($"//{nameof(LoginPage)}", true);
             });
         } else {
             await Shell.Current.GoToAsync($"//{nameof(LoginPage)}", true);
         }
     } else {
         var loggedUser = JsonSerializer.Deserialize<DemyUser>(currentUserAsJson);
         FlyoutHeaderHelper.CreateFlyoutHeader(loggedUser);
         WelcomePageViewModel welcomePageViewModel = new(loggedUser);
         await Shell.Current.GoToAsync($"//{nameof(WelcomePage)}", true);
     }

in the startup page I have a method, to check if I am authenticated.But what I do not understand I the error that I get

System.InvalidOperationException: 'Unable to resolve service for type 'DemyAI.Models.DemyUser' while attempting to activate 'DemyAI.ViewModels.WelcomePageViewModel'.'

DemyUser is a class, not a service nor an interface.

builder.Services.AddSingleton<HttpClient>();
builder.Services.AddSingleton(AudioManager.Current);
builder.Services.AddSingleton<IAppService, AppService>();
builder.Services.AddSingleton(typeof(IDataService<>), typeof(DataService<>));
builder.Services.AddSingleton<IAuthenticationService, AuthenticationService>();
builder.Services.AddSingleton<IHttpService, HttpService>();
builder.Services.AddSingleton(Connectivity.Current);
builder.Services.AddSingleton(firebaseAuthClient);
builder.Services.AddSingleton<AppShell>();
builder.Services.AddSingleton<NoInternetPage>();
builder.Services.AddSingleton<LoginPage>();
builder.Services.AddSingleton<WelcomePage>();
builder.Services.AddSingleton<NewLecturePage>();
builder.Services.AddSingleton<NewTestPage>();
builder.Services.AddSingleton<ScheduleLecturePage>();
builder.Services.AddSingleton<ScheduleTestPage>();
builder.Services.AddSingleton<NotificationsPage>();
builder.Services.AddSingleton<JoinMeetingPage>();
builder.Services.AddSingleton<ManageCoursePage>();
builder.Services.AddSingleton<StartupPage>();
builder.Services.AddSingleton<RoleSelectionPage>();
builder.Services.AddSingleton<AppShellViewModel>();
builder.Services.AddSingleton<LoginPageViewModel>();
builder.Services.AddSingleton<WelcomePageViewModel>();
builder.Services.AddSingleton<NewLecturePageViewModel>();
builder.Services.AddSingleton<NewTestPageViewMode>();
builder.Services.AddSingleton<ScheduleLecturePageViewModel>();
builder.Services.AddSingleton<ScheduleTestPageViewModel>();
builder.Services.AddSingleton<JoinMeetingPageViewModel>();
builder.Services.AddSingleton<ManageCoursePageViewModel>();
builder.Services.AddSingleton<NotificationsPageViewModel>();
builder.Services.AddSingleton<StartupPageViewModel>();
builder.Services.AddSingleton<FlyoutHeaderViewModel>();
builder.Services.AddSingleton<RoleSelectionPageViewModel>();

I also tried this.

WelcomePage welcomePage = new(new WelcomePageViewModel(loggedUser));

and become I need to crate shell Items dynamically

I added this

 private DemyUser? loggedUser;
    public WelcomePageViewModel(DemyUser? loggedUser) {
        this.loggedUser = loggedUser;
        GetShellItems(loggedUser?.CurrentRole);
    }
    private void GetShellItems(string? currentRole) {
        switch(currentRole) {
            case nameof(Role.Teacher):
                break;
            case nameof(Role.Coordinator):
                break;
            case nameof(Role.Student):
                Debug.WriteLine("d");
                break;
            default:
                break;
        }
    }
}

Answer 1

I fix it, since we are using dependency injection. We cannot send classes thru the contractor of the page.