Is it possible to get successful results from a Task.WhenAll when one of the tasks fails?

Question

Given the following:

var tPass1 = Task.FromResult(1);
var tFail1 = Task.FromException(new ArgumentException(\"fail1\"));
var tFail2 = Task.FromExc         


        

Answer 1

Playing around with @Theodor Zoulias's powerfull and elegant solution pushed me to something. It looks hacky, but still works. One can continue Task.WhenAll with something that will not throw an exception for sure (e.g. _ => { }) and Wait that something.

var cts = new CancellationTokenSource();
cts.Cancel();
var canceled = Task.Run(() => 1, cts.Token);

var faulted = Task.FromException(new Exception("Some Exception"));

var ranToCompletion = Task.FromResult(1);

var allTasks = new[] { canceled, faulted, ranToCompletion };

// wait all tasks to complete regardless anything
Task.WhenAll(allTasks).ContinueWith(_ => { }).Wait();

foreach(var t in allTasks)
{
    Console.WriteLine($"Task #{t.Id} {t.Status}");
    if (t.Status == TaskStatus.Faulted)
        foreach (var e in t.Exception.InnerExceptions)
            Console.WriteLine($"\t{e.Message}");
    if (t.Status == TaskStatus.RanToCompletion)
        Console.WriteLine($"\tResult: {t.Result}");
}

Output looks like this:

Task #2 Canceled
Task #1 Faulted
        Some Exception
Task #5 RanToCompletion
        Result: 1