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Base Persistent Classes

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This topic describes the base persistent classes that can be used in XAF applications when creating a data model with XPO.

The following table lists the base persistent classes you can inherit from when you define persistent business classes:

Persistent Class Namespace Supported Concurrency Control Contains the Auto-Generated Primary Key Property Supports Deferred Deletion
XPLiteObject DevExpress.Xpo None ("Last in wins") No No
XPBaseObject DevExpress.Xpo Optimistic No No
XPCustomObject DevExpress.Xpo Optimistic No Yes
XPObject DevExpress.Xpo Optimistic Yes. Integer type. Yes
BaseObject DevExpress.Persistent.BaseImpl Optimistic Yes. Guid type. Yes
DCBaseObject DevExpress.ExpressApp.Xpo Optimistic Yes. Guid type. Yes

The BaseObject class is used when creating business classes from the XPO Business Object template. It is a feature-rich persistent class that supports the optimistic concurrency control (optimistic locking mechanism).

We recommend using the XPObject class if your business class should use the integer type primary key. This class also supports optimistic concurrency control.

You need to define the primary key property in the business class declaration if you are using classes which do not have the auto-generated primary key property. The following code snippet illustrates this:

using System.ComponentModel;
//...
[DefaultClassOptions]
public class MyClass : XPLiteObject {
   public MyClass(Session session) : base(session) { }
   [Key(AutoGenerate = true), Browsable(false)]
   public int Oid { get; set; }
   public string MyProperty {
      get { return GetPropertyValue<string>("MyProperty"); }
      set { SetPropertyValue<string>("MyProperty", value); }
   }
}

If you need to consider whether to use a base class that supports the deferred deletion feature, refer to the XPO documentation: Deleting Persistent Objects.

You can implement a custom base persistent class. To learn more, refer to the How to: Implement a Custom Base Persistent Class help topic.

See Also