Async Task gives warning, (without) Async Task gives error

Question

This is probably a more of a finesse question but I have the following method inside a ViewComponent class

public async Task<IViewComponentResult> InvokeAsync()
{
    return View();
}

but the name InvokeAsync is underlined and gives the following warning

This async method lacks 'await' operators and will run synchronously. Consider using the 'await' operator to await non-blocking API calls, or 'await Task.Run(...)' to do CPU-bound work on a background thread

but if I try removing the async from the method then return View() is underlined with red and outputs the following error

'Microsoft.AspNetCore.Mvc.ViewComponents.ViewViewComponentResult' to 'System.Threading.Tasks.Task' MVCStateManagement

So my question is what approach should I take? Let the async there indiferently of the warning, or is there a workaround / fix for this warning? Does it have that much of an impact on my project?

Thanks!

Answer 1

It's unclear why the method was defined as an async method that returns a Task<IViewComponentResult> in the first place.

Since the method seems to be truly synchronous and simply returns a view, you should probably define it like this:

public IViewComponentResult Invoke()
{
    return View();
}

A synchronous method doesn't magically become asynchronous just because you add the async keyword to it.

If you are implementing an interface and cannot change the signature of the method, you could use the Task.FromResult method to return an already completed task (you should still remove the async keyword):

public Task<IViewComponentResult> InvokeAsync()
{
    return Task.FromResult<IViewComponentResult>(View());
}

Answer 2

The method runs on a Task of ViewcomponentResult. You can call it without async by using this:

public Task<IViewComponentResult> InvokeAsync()
{
  return Task.FromResult<IViewComponentResult>(View());
}

Your warning will no longer show and your code will run. You could also leave it. Either will have no impact on the performance of your project.