Converting (Mapping) a List of an entity to another reference explitically

Question

How do I convert/map a list from one entity to another reference explicitly. Here’s an example I was able to perform with an entity:

public static explicit operator UserResponse(Entities.User entity)
{
        return new UserResponse()
        {
            Id = entity.Id,
            Role = entity.Role,
            Email = entity.Email,
            UserStatus = entity.UserStatus
        };
}

So I can convert explicitly within a business rule:

(UserResponse) await _userRepository.Create((User) user);

I would like to do this for a list, rather than using the method below:

public static List<UserResponse> FromIList<User>(IList<Entities.User> entity)
        {
            return entity.Select(item => new UserResponse()
            {
                Id = item.Id,
                Role = item.Role,
                Email = item.Email,
                UserStatus = item.UserStatus
            }).ToList();
        }
    }

Answer 1

Having explicit conversions, just do the following:

//Convertendo B para A
List<B> listB = listA.Select(a => (B)a).ToList();

//Convertendo A para B
List<A> listA = listB.Select(b => (A)b).ToList();

With the above example I am assuming you have the classes A and B:

public class A
{
    public int Id { get; set; }
    public string Role { get; set; }
    public string Email { get; set; }

    public static explicit operator A(B b)
    {
        return new A
        {
            Id = b.id_b,
            Role = b.prop_b1,
            Email = b.prop_b2
        };
    }
}

public class B
{
    public int id_b { get; set; }
    public string prop_b1 { get; set; }
    public string prop_b2 { get; set; }

    public static explicit operator B(A a)
    {
        return new B
        {
            id_b = a.Id,
            prop_b1 = a.Role,
            prop_b2 = a.Email
        };
    }
}

See the example in fiddle.

Answer 2

As long as the conversions are valid, you can use the extension method Cast linq.

Considering the code of this answer, would look like this.

var listB = listA.Cast<B>().ToList();
var listA = listB.Cast<A>().ToList();