Difference between Func<T, Task> and anonymous async await Action<T>

Question

I am developing on ASP.NET Core Blazor and sometimes I look on GitHub to learn something. This question isn't strictly related to Blazor, but I saw a lot of Blazor developers doing what I am going to explain.

I noticed that some components accept an Action<T> as a parameter and others accept a Func<T, Task>.

/* example */

public class MyComponentA : ComponentBase 
{
    [Parameter] public Action<T> OnClick {get; set;}

    //... other methods
}

public class MyComponentB : ComponentBase 
{
    [Parameter] public Func<T, Task> OnClickAsync {get; set;}

    //... other methods
}

What I understood is that you should bind Action<T> to a no-async/await method and Func<T, Task> to an async/method. So far so good.

However, I see that someone is used to pass an async/await anonymous function as Action<T>, like OnClick=@(async (item) => await Foo(item)). Sometimes, I have passed an anonymous async/await function as Action too, and it works.

• Is it correct?

• Is there any kind of side effect?

• Is an Action<T> that invokes an anonymous async/await function, an asynchronous call?

Answer 1

Action<T> does not allow a return value, and only methods that return an awaitable type (usually Task or Task<T>) can be awaited.

Therefore, if you use pass an asynchronous method as Action<T> it will always be fire and forget.

Using Func with Task as a return value may be awaited, depending on how the method is implemented.