WPF WindowLess MessageBox

Question

I'm attempting to convert a very small C# console application to WPF application. It takes in some parameters, does some work, and may bring up a MessageBox.

I'm moving it from a console app to WPF because it should run invisible, unless it has an error message.

The hitch, so far, has been getting it to show the MessageBox. The following is the really short version, that compiles, runs... but does not show the MessageBox.

namespace MyApp{
  public class EntryPoint {
    [STAThread]
    public static void Main(string[] args) {
        App app = new App();
        app.Run();
        MessageBox.Show("test", "test", MessageBoxButton.YesNo, MessageBoxImage.Question);
    }
  }
}

Anyone know how to get that pesky MessageBox to show, without having a main program window?

`app.Run` won't complete until after the program exits so the the call to `MessageBox` won't execute as you expect. You will have to move the `MessageBox` someplace else in your code. We can't really me more specific because you haven't shown us any other code. — Bradley Uffner, Apr 11 '16 at 19:43
That is literally all there is to it. I'm completely new to WPF and not certain how to build a windowless app. — ltwally, Apr 12 '16 at 01:14
You could put all your code in the application startup event in app.xaml, and get rid of all the forms. — Bradley Uffner, Apr 12 '16 at 06:14
This is literally my first WPF app, and haven't a clue how to do what you're talking about. The only code in the XAML file is the default that VS created... and that all has to do with the main program window, which I have since deleted from the CS file. — ltwally, Apr 14 '16 at 12:35

score 0 · Answer 1 · answered Apr 14 '16 at 13:28

Your best bet may be to try and run the code in the application's Startup event. Keep in mind that WPF wasn't really designed to be used this way, so there may be some odd quirks.

Start by opening "App.xaml` in the solution explorer. The root of the XAML should look something like this:

<Application x:Class="Configurator.Application.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:local="clr-namespace:FoodSafetyConfigurator"
             xmlns:s="clr-namespace:Configurator.Application.Properties"
             StartupUri="MainForm.xaml">

Remove the StartupUri="MainForm.xaml" attribute, and replace it with Startup="App_OnStartup". That will stop WPF from displaying a window by default, and hook the startup event to a method in "App.xaml.cs" called App_Starup.

Now expand "App.xaml" in solution explorer, and open "App.xaml.cs"; this is the code behind file for "App.xaml". Add a method called App_OnStartup, which will be the target of the event we attached earlier. It should look something like this:

private void App_OnStartup(object sender, StartupEventArgs e)
{
    //Your code goes here.
}

Add any code you want to run in here. Any message boxes you display with MessageBox.Show() should display correctly, but I haven't actually tested it.

I apologize... but this really is my first WPF app, ever. And I'm not sure where to put the function you described inside the App.xaml.cs file. — ltwally, Apr 14 '16 at 15:30
Yes, in this scenario `App_OnStartp` would act as the`Main` method from your console application. — Bradley Uffner, Apr 14 '16 at 17:14
Error 1 'MyApp.App' does not contain a definition for 'App_OnStartup' and no extension method 'App_OnStartup' accepting a first argument of type 'MyApp.App' could be found (are you missing a using directive or an assembly reference?) — ltwally, Apr 14 '16 at 18:47
Did you add the `App_OnStartup` method to the `App` class in App.xaml.cs? — Bradley Uffner, Apr 14 '16 at 18:50

score 0 · Answer 2 · answered Apr 21 '16 at 16:44

0

I ended up going with a standard Windows Forms application, and just removed the form. Figuring out how to make WPF do this was time consuming, frustrating and ultimately a failure. Forms may not be the new hotness, but it works.

answered Apr 21 '16 at 16:44

ltwally

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WPF WindowLess MessageBox

2 Answers2