Await the result of Task using reflection in a non-generic method

Question

Consider the following case:

class A
{
    public int Id;
}

class B : A
{

}

class Main
{
    public async Task Create(Type type)
    {
                 


        

Answer 1

As per my comment:

Unlike interfaces, concrete types such as Task<TResult> cannot be covariant. See Why is Task not co-variant?. So Task<B> cannot be assigned to a Task<A>.

The best solution I can think of is to use the underlying type Task to perform the await like so:

var task = (Task)method.Invoke(this, new object[] { "humpf" });
await task;

Then you can use reflection to get the value of the Result:

var resultProperty = typeof(Task<>).MakeGenericType(type).GetProperty("Result");
A a = (A)resultProperty.GetValue(task);
return a.Id;

Answer 2

The above solution really helped me. I made a small tweak to the @Lukazoid solution...

var resultProperty = typeof(Task<>).MakeGenericType(type).GetProperty("Result");
A a = (A)resultProperty.GetValue(task);

to

dynamic a = task.GetType().GetProperty("Result")?.GetValue(task);