Async Await Return Task Null .Net Core

Question

I've a method like this:

public async Task<Response> HandleRequest(string connectionId, Request request)
{
  if (request is AuthorizeRequest)
  {
    return await _handler.HandleRequest(connectionId, request as AuthorizeRequest);
  }

  if (request is ChangeConfigurationRequest)
  {
    return await _handler.HandleRequest(connectionId, request as ChangeConfigurationRequest);
  }

  return await Task.FromResult<Response>(null);  //My question is here
}

My question is: Should I return return await Task.FromResult(null); or retun null; Because if request is not 'AuthorizeRequest' and 'ChangeConfigurationRequest'

Tks all for helps

Ricardo Peres · Accepted Answer · 2020-02-11 16:22:56Z

2

Since your method is marked as async, you should return null.

answered Feb 11, 2020 at 16:22

Ricardo Peres

14.8k5 gold badges64 silver badges78 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

NyTiKaTu Over a year ago

Tks Peres, I search from many resources and it said that we should not return null in Task. Is it right?

NyTiKaTu Over a year ago

And how about my method like this: ``` public Task<Response> HandleRequest(string connectionId, Request request) { return Task.FromResult<Response>(null); }```

Ricardo Peres Over a year ago

Yes, that would be correct, IMO, without the async modifier.

Stephen Cleary · Accepted Answer · 2020-02-12 02:24:51Z

2

I search from many resources and it said that we should not return null in Task. Is it right?

Methods that return a task should never return a null task. However, what you want to do is return a (non-null) task that contains a result value of null. That's fine; it's completely different than returning a null task.

For your original code, use return null;. Do not ever use await Task.FromResult(...).

answered Feb 12, 2020 at 2:24

Stephen Cleary

460k78 gold badges721 silver badges858 bronze badges

2 Comments

RTF Over a year ago

I know this is an old post, but when would one ever need to use Task.FromResult()? Is it only when we are dealing with a method that is not async returns a Task? Is there ever a reason in modern C# to have a method that returns a Task without also being async anyway?

Stephen Cleary Over a year ago

It's rare. Most of my use cases are test stubs implementing async interfaces.

Collectives™ on Stack Overflow

Async Await Return Task Null .Net Core

2 Answers 2

3 Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related