AppDev01

int pageNumber = (Page ?? 1);

Here you are using null-coalescing operator, this will Set pageNumber to the value of Page if Page is NOT null; otherwise, if page = null, set pageNumber  to 1.

This can be rewritten like below

int pageNumber = 0;
            if (Page != null)
            {
                pageNumber = Page;
            }
            else
            {
                pageNumber = 1;
            }