How do you bring Denormalized Values Into your Business Objects?

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;
   }
}