如何在Windows 8.1中使用SearchBox时优雅地处理TaskCancelledException

Question

I am using a searchbox to which I will load a list of names.

My code behind

private async void SearchBox_SuggestionsRequested(SearchBox sender, SearchBoxSuggestionsRequestedEventArgs args)
    {
        if (string.IsNullOrEmpty(args.QueryText))
        {
            return;
        }
        var collection = args.Request.SearchSuggestionCollection;
        if(oldquery != args.QueryText && args.Request.IsCanceled == false)
        {
            var deferral = args.Request.GetDeferral();
            try
            {
                oldquery = args.QueryText;

                var listOfBanks = await addFIPageViewModel.GetBanksOnQuery();

                foreach (Institution eachBank in listOfBanks)
                {
                    collection.AppendQuerySuggestion(eachBank.Name);
                }
            }

            //JUST Logging and ignoring. Can I handle it in a better way
            catch(Exception e)
            {
                Debug.WriteLine(e.StackTrace);
            }
            finally
            {
                deferral.Complete();
            }

        }
    }

An exception of type 'System.Threading.Tasks.TaskCanceledException' A task was canceled. is occuring in the line

var listOfBanks = await addFIPageViewModel.GetBanksOnQuery();

which I am simply ignoring as you see.

Is there a better way to handle this?

I was unable to identify the root cause of this problem. Could someone guide if this is the right way to call an async method inside SearchSuggestionRequested.

Answer 1

Your code looks fine to me. I'd catch the TaskCanceledException explicitly though to make sure I do not ignore other exceptions unintentionally.

try
{
    // like above 
}
catch(TaskCanceledException e)
{
    Debug.WriteLine("Task cancelled: " + e.Message);
}
finally
{
    deferral.Complete();
}