how to make asynchronous static method with same generic array param and same generic array return type

Question

I want to do all of the same code twice, but just for two different objects. I am getting these objects from a SOAP API (rather outdated one). I want to avoid writing duplicate code over and over again. I'll be taking my original object and manipulating it a lot (all the same way) the only difference is that the object type is the difference, so that's why I need to make a generic object. I want it to return the same type as it takes as a parameter. I am having an issue that if I do code like this

public static class ParamsHelper<T>
{
    public static async Task<T[]> Whatever(T[] rptParams)
    {
        //do some stuff to rptparams
        return rptParams;
    }
}

//  then I call it like this below:
var params = await  ParamsHelper.Whatever<ItemP[]>(new ItemP[]{});

//  it says can't convert type ItemP[] to type ItemP[][].

Additionally, I am using LINQ to do all of the manipulating. I would love advice on how to access the object fields (maybe reflection?)

Answer 1

You have to declare the generic type on the method.

public static async Task<T[]> Whatever<T>(T[] rptParams)

The usage generally is implied from usage so you don't have to pass it.

if you do have to pass it, dont make it an array.

ParamsHelper.Whatever<ItemP>(new ItemP[] { });