How do you implement an async action delegate method?

Question

A little background information.

I am learning the Web API stack and I am trying to encapsulate all data in the form of a "Result" object with parameters such as Success and ErrorCodes.

Different methods however, would produce different results and error codes but the result object would generally be instantiated the same way.

To save some time and also to learn more about async/await capabilities in C#, I am trying to wrap all the method bodies of my web api actions in an asynchronous action delegate but got caught in a bit of a snag...

Given the following classes:

public class Result
{
    public bool Success { get; set; }
    public List<int> ErrorCodes{ get; set; }
}

public async Task<Result> GetResultAsync()
{
    return await DoSomethingAsync<Result>(result =>
    {
        // Do something here
        result.Success = true;

        if (SomethingIsTrue)
        {
            result.ErrorCodes.Add(404);
            result.Success = false;
        }
    }
}

I want to write a method that performs an action on a Result object and return it. Normally through synchronous methods it would be

public T DoSomethingAsync<T>(Action<T> resultBody) where T : Result, new()
{
    T result = new T();
    resultBody(result);
    return result;
}

But how do I transform this method into an asynchronous method using async/await?

This is what I have tried:

public async Task<T> DoSomethingAsync<T>(Action<T, Task> resultBody) 
    where T: Result, new()
{
    // But I don't know what do do from here.
    // What do I await?
}

Answer 1

The async equivalent of Action<T> is Func<T, Task>, so I believe this is what you're looking for:

public async Task<T> DoSomethingAsync<T>(Func<T, Task> resultBody)
    where T : Result, new()
{
  T result = new T();
  await resultBody(result);
  return result;
}

Answer 2

So I believe the way to implement this is:

public Task<T> DoSomethingAsync<T>(Action<T> resultBody) where T : Result, new()
{
    return Task<T>.Factory.StartNew(() =>
    {
        T result = new T();
        resultBody(result);
        return result;
    });
}