捕获从ShowAsync（）外部的ContentDialog的单击处理程序引发的异常

Question

Currently if I throw an exception somewhere down the call stack from the click handler it will crash the application. Is there a way to allow the exception out of the ContentDialog.ShowAsync()?

    public async Task<bool> ShowLoginDialogAsync(LogInType loginType) {         
        var loginDialog = new LoginDialog(loginType);
        try {
            await loginDialog.ShowAsync(); <-- Exception thrown in click handler will crash the app
        }
        catch { } <-- I'd like to cach login exceptions here rather than be limited the ContentDialog return result
        return loginDialog.Result;
    }

    public sealed partial class LoginDialog {

        private async void OkClicked(ContentDialog contentDialog, ContentDialogButtonClickEventArgs args) {
            await Validate(); <-- last chance to catch an exception or crash?
        }
}

Answer 1

The OkClicked code doesn't run inside the loginDialog.ShowAsync() , it runs independently. You have to wrap the call to Validate in a try/catch if you want to get the exception from it, or it will just propagate to the context and, uncaught, crash the application.

Answer 2

I've currently decided to use the following strategy in several places to work with converting our WinForms/WPF app to UWP. I wouldn't normally do this and I may choose to factor it out later, but this code allows me to propagate exceptions out of the ContentDialog and abide the async/await pattern:

public sealed partial class LoginDialog {
    public Exception Exception { get; private set; }

    private async void OkClicked(ContentDialog contentDialog, ContentDialogButtonClickEventArgs args) {
            try {
                await Validate();
            }
            catch (Exception e) {
                Exception = e;
            }
        }
}

public async Task<bool> ShowLoginDialogAsync(LogInType loginType) {

            var loginDialog = new LoginDialog(loginType);

            await loginDialog.ShowAsync();

            switch (loginDialog.Exception) {
                case null:
                    break;
                default:
                    throw loginDialog.Exception;
            }

            return loginDialog.Result;
        }