MVVM Toolkit - How do I get a MessageBox to display an error from the callback if the WCF Service fails

I am using the MVVM Toolkit to build my WP7 apps and I am trying to get a MessageBox to display an error if the WCF service fails.

Here is the code I have in my ServiceHelper layer:

        public void GetRandomBibleVerseById(Action<Bible, Exception> callback)
    {
        var client = new StoneFalconClient();

        client.GetRandomBibleVerseByIdCompleted += (s, e) =>
            {
                var userCallback = e.UserState as Action<Bible, Exception>;

                if (userCallback == null)
                {
                    return;
                }

                if (e.Error != null)
                {
                    userCallback(null, e.Error);
                    return;
                }

                userCallback(e.Result, null);
            };

        client.GetRandomBibleVerseByIdAsync(callback);
    }

I tried placing a try/catch around the service call by doing something like this but I don't get any message box to show up with the error. Here is my MainViewModel:

        public MainViewModel()
    {
        if (IsInDesignMode)
        {
            BibleVerse = LoadDebugVerse();
        }
        else
        {
            try
            {
                ServiceHelper helper = new Serv开发者_开发百科iceHelper();

                helper.GetRandomBibleVerseById((bibleVerse, error) =>
                {
                    Bible displayVerse = LoadDisplayVerse(bibleVerse);
                    BibleVerse = displayVerse;

                    TestamentBookChapterVerse = displayVerse.Testament + ": " + displayVerse.Book + " " + displayVerse.Chapter + ":" + displayVerse.Verse; ;
                });
            }
            catch (Exception ex)
            {
                ErrorMessage = new RelayCommand<String>(m => MessageBox.Show("Error: Click refresh to try again"));
            }
        }
    }

I am binding the xaml in the xaml page to the viewModel. I suspect that I shouldn't be using the try/caatch but instead inspecting e.Error but I have no idea how to do that.

Any help would be appreciated, I have been searching forever for an answer with no luck.

RJ,

Your client object (of type StoneFalconClient) should have an AsyncCompleted event that you can register a handler for. In your OnAsyncCompleted handler, there should be an Error field in the EventArgs parameter.

Good luck
Jim McCurdy