WPF : How can i show my login window(project imported) before my application window?

Question

I have made a project for a login WPF application that basically performs a database connection. Now I am developing an application (always in WPF) that need this login project to start. I have added the Login.Exe to the reference in my current project, but I can't find a way to force the start with the login and only after that run my MainWindow().

I'm currently trying something like this

namespace Administrator
{ 
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            Window login = new Login.MainWindow();
            login.Show();
        }
    }
}

My mainwindow.xaml has empty content, and this piece of code it shows the login form, but also a blank window. How can I achieve my goal?

Answer 1

Set in the App.xaml the "ShutdownMode" and the "StartupUri":

   <Application x:Class="MyApp.App"
                xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                xmlns:local="clr-namespace:MyApp"
                ShutdownMode="OnExplicitShutdown"
                StartupUri="Login.xaml">

The "StartupUri" is your login form.

Answer 2

You can achieve this with the following pattern.

In your App.xaml change StartupUri="MainWindow.xaml" to Startup="ApplicationStart" and in your App.xaml.cs create the method ApplicationStart.

private void ApplicationStart(object sender, StartupEventArgs e)
{
    Window login = new Login.MainWindow();
    login.Show();

    // Determine if login was successful
    if (login.DataContext is LoginViewModel loginVM)
    {
        if (!loginVM.LoginSuccessful)
        {
            // handle any cleanup and close/shutdown app
        }
    }

    //show your MainWindow
}

I prefere this pattern because you can eg setup your DI container in the ApplicationStart or anything else you want to before your main view is shown.