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How do you bring Denormalized Values ​​to your business objects?

I have two tables.

Order - with Columns OrderID, OrderStatusID
OrderStatus - with columns OrderStatusID, Description

I have an Order object that calls the database and populates 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 designs?

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5 answers


I usually prefer to treat requests as Value objects . I am also using the 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;
   }
}
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The system I'm currently working with instantiates another business object and sets an id. Then another business object is retrieved when it is in use. eg.

Order properties



int OrderId = 5
int OrderStatusId = 3
OrderStatus OrderStatus_ref
{
get
{
    if OrderStatus_ref == null
        OrderStatus_ref = new OrderStatus(OrderStatusId)
    return OrderStatus_ref
}
}

This is generally an idea.

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You can use a SQL select statement with the Join to the OrderStatus table and include yo columns from each table ...

Select O.OrderId, O.OrderStatusId, S.Descriptiuon
From Order O
    Join OrderStatus S 
        On S.OrderStatusId = O.OrderStatusId
Where OrderId = 23 -- or whatever
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Is this a one-to-one relationship between Order and OrderStatus? I suppose it depends on the purpose, why would you have an OrderStatus table as I would argue that there is actually no need for a separate OrderStatus table?

Basically, this whole table gives you the ability to change the description of the order status. From code, you should write code according to a predefined OrderStatusID (from initial data?) Or using a description. If so, why not have an OrderStatus column in the Order table, which is an integer and can represent the enumeration type?

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The My Order object is likely to include a state description field (read-only [for non-inner classes]) as well as any other similar fields.

Under the hood, my recipients (like LoadByID, LoadAll, etc.) will probably use a View (like OrdersView) that contains all of these descriptive fields. These description fields are read-only, so you don't accidentally set these fields thinking you can save your changes to the database.

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