WPF UI不从ViewModel / Caliburn.Micro更新

Question

I have a caliburn Micro application, in which I'm loading several data tables in the bootstrapper. I'm injecting this into MEF for use later in the application.

I want to show the user with a splash screen of the progress. This is all working fine so far. I'm using the EventAggregator to have the individual classes throw messages to the Splash Screen ViewModel, however the UI thread seems not the working to update my text label. My property is set fine, and i'm calling the NotifyOfPropertyChange, however my window seems to be frozen, the get ancestor on my bound property is not being called.

public string Message
    {
        get
        {
            return this.message;
        }
        set
        {
            this.message = value;
            //new System.Action(() => NotifyOfPropertyChange(() => Message)).BeginOnUIThread();
            //App.Current.Dispatcher.Invoke(() => NotifyOfPropertyChange("Message"));
            NotifyOfPropertyChange(() => Message);
        }
    }


    public void Handle(StartupNotification message)
    {
        Message = message.Message;
    }

The Handle comes from the Caliburn.Micro IHandle EventAggregrator. The data is loaded in the bootstrapper, I assume this thread is seperate from the UI Thread, but i'm not personally creating any threads.

In my bootstrapper I load as follows:

events.Publish(new StartupNotification("Loading Feeds..."));
batch.AddExportedValue<IFeedService>(new FeedService());

I have tried to trigger the UI by indirect measures, but for some reason my main screen stays frozen. Can anyone indicate what I'm doing wrong?

Best Regards, Martin

Answer 1

The bootstrapper runs in the UI thread, I assume you have soemthing like this:

 protected override void OnStartup(object sender, System.Windows.StartupEventArgs e)
 {
     DisplayRootViewFor<ShellViewModel>();
     RunLongLoadingOperation();
 }

You should do something like

 protected override void OnStartup(object sender, System.Windows.StartupEventArgs e)
 {
     DisplayRootViewFor<ShellViewModel>();
     var task = Task.Factory.StartNew(RunLongLoadingOperation);

     // task error handling omitted, 
     // if your long operation can throw an exception you should 
     // add an oncompleted handler and do something with it or the
     // app will be brought down when the task gets GC'd
 }

Answer 2

This is now solved, I have moved my DB loads into a background worker, and added Thread.Sleep in there to allow some time for the UI to update on the ProgressChanged events.

I expected .NET to take care of this since I moved it to a background worker already, but oh well.