WhenAll for anonymous type containing a Task

Question

Is it possible to await a anonymous object (or Tuple, don't care) that contains a Task...better to explain with code...

Lets says we have this:

async Task<Item> GetItem(int i);

Basic case (works):

var itemTasks = new []{1,2,3}.Select(i => GetItem(i)).toArray();
Item[] items = await Task.WhenAll(itemTasks);

what I want to do

var itemTasks = new []{1,2,3}
    .Select(i => new { MyItem = GetItem(i), TheNumber = i })
    .toArray();
//some way to wait for all and get a collection of<anynomous type above> 

Answer 1

You just need to make your lambda async:

var itemTasks = new []{ 1, 2, 3 }
    .Select(async i => new { MyItem = await GetItem(i), TheNumber = i });

var anonymousObjects = await Task.WhenAll(itemTasks);

The async lambda will implicitly return a Task<AnonymousObject>.

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As an aside, your ToArray() is superfluous, because Task.WhenAll enumerates the Tasks anyway.