using System;

abstract class DbContext {} // to oczywiscie jest z EF

class UserDTO
{
   public string IPAddress { get; set; }
   public ICollection<Settings> Settings { get; set; }
   public string UserName { get; set; }
}

class UserService
{
   public string IPAddress { get; set; }
   public ICollection<Settings> Settings { get; set; }
   public string UserName { get; set; }
}

class MyContext : DbContext
{
   public DbSet<User> Users { get; set; }
   public DbSet<Settings> Settings { get; set; }

   public UserService GetUser(string IPAddress)
   {
		var result = Users.FirstOrDefault(x => x.IPAddress = IPAddress);
		if (result == null)
		{
			throw new Exception() //tutaj specyficzny exp
		}
		return Mapper.Map(result);
   }
}

public class Test
{


	public static void Main()
	{
		// your code goes here
	}
}