In .Net Core after Task.WhenAll, to get data is .Result is fine or need use await again to get data?

Question

await Task.WhenAll(existingServiceTask, cartServiceTask).ConfigureAwait(false);
var existingService = existingServiceTask.Result; //Is this ok? Any deawback of this?
var carInfo = await cartServiceTask;              //Or this is better?

Try to understand after await WhenAll, if .Result is fine or has any drawbacks?

And some user here in SO adivses [not to await twice](https://blog.marcgravell.com/2019/08/prefer-valuetask-to-task-always-and.html) — Pac0, May 18 '20 at 18:45
I'd recommend simply to store the result of `await WaitAll`, though — Pac0, May 18 '20 at 18:46
Does this answer your question? [Get result from Task.WhenAll](https://stackoverflow.com/questions/31554080/get-result-from-task-whenall) — Pac0, May 18 '20 at 18:47
@Pac0 that *is* referring to the difference between `Task` and `ValueTask`, but yes: it is a bad practice to get into — Marc Gravell, May 18 '20 at 18:47
@MarcGravell Ah, thanks for clarifying this to me, author :) — Pac0, May 18 '20 at 18:48

score 1 · Accepted Answer · answered May 18 '20 at 19:18

The best way to do this is as follows.

await Task.WhenAll(existingServiceTask, cartServiceTask).ConfigureAwait(false);
var existingService = await existingServiceTask;
var carInfo = await cartServiceTask;

Using await will protect you if you forget to put this task in Task.WhenAll

In .Net Core after Task.WhenAll, to get data is .Result is fine or need use await again to get data?

1 Answers1