Cleanest Way To Map Entity To DTO With Linq Select?

Question

I\'ve been trying to come up with a clean and reusable way to map entities to their DTOs. Here is an example of what I\'ve come up with and where I\'m stuck.

Answer 1

You could either use AutoMapper or write extension methods like these:

public static class PersonMapper
{
    public static PersonDTO ConvertToDTO(this Person person)
    {
        return new PersonDTO { ID = person.ID, Name = person.Name, Address = person.Address.ConvertToDTO() };
    }

    public static IEnumerable ConvertToDTO(this IEnumerable people)
    {
        return people.Select(person => person.ConvertToDTO());
    }
}

public static class AddressMapper
{
    public static AddressDTO ConvertToDTO(this Address address)
    {
        return new AddressDTO { ID = address.ID, City = address.City };
    }

    public static IEnumerable ConvertToDTO(this IEnumerable
 addresses)
    {
        return addresses.Select(address => address.ConvertToDTO());
    }
}

You could then map a Person object to a PersonDTO object like this:

public class Program
{
    static void Main(string[] args)
    {
        Person person = new Person { ID = 1, Name = "John", Address = new Address { ID = 1, City = "New Jersey" } };
        PersonDTO personDTO = person.ConvertToDTO();
        Console.WriteLine(personDTO.Name);
    }
}