Question

I have two Tables.

Order – With Columns OrderID, OrderStatusID
OrderStatus – With Columns OrderStatusID, Description

I have an Order Object which calls to the database and fills its properties for use in my code. Right now I have access to Order.OrderStatusID, but in my application I really need access to the ‘Description’ field.

How do you handle this elegantly with good OO design?

Answer 1

Usually I prefer to handle lookups as Value objects. I also use Null Object pattern.

public class Order {   private int statusID;    public OrderStatus Status {     get {       return OrderStatus.Resolve(statusID);     }     set {       statusID = value != null ? value.ID : null;     }   } }  public class OrderStatus {    public static OrderStatus Resolve(int statusID)    {      OrderStatus status = null;      // read from cache or DB      ...      // if not found return Null object      if (status == null)        status = new OrderStatus(null, string.Empty);      return status;    } }