c# - 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<int>(new ArgumentException("fail1"));
var tFail2 = Task.FromException<int>(new ArgumentException("fail2"));

var task = Task.WhenAll(tPass1, tFail1, tFail2);
task.Wait();

the call to task.Wait() throws an AggregateException, whose inner exceptions contain the fail1 and fail2 exceptions. But how can I access the tPass1 successful result?

Is this possible?

I'm aware that I can get the result from the individual task after the WhenAll has finished, via tPass1.Result however is there a way to get them in an array to avoid having to manually track all the things feeding into the WhenAll?

Answer 1

Maybe

public async Task<Task[]> RejectFailedFrom(params Task[] tasks)
{
    try
    {
        await Task.WhenAll(tasks);
    }
    catch(Exception exception)
    {
        // Handle failed tasks maybe
    }

    return tasks.Where(task => task.Status == TaskStatus.RanToCompletion).ToArray();
}

Usage

var tasks = new[]
{
    Task.FromResult(1),
    Task.FromException<int>(new ArgumentException("fail1")),
    Task.FromException<int>(new ArgumentException("fail2"))
};

var succeed = await RejectFailedFrom(tasks);
// [ tasks[0] ]