Occurs before a new object is persisted to the data source.
Assembly: System.Web.Entity (in System.Web.Entity.dll)
The event is raised before a new object is persisted to the data source. The event enables you to modify or verify the object being added, add a different object, or cancel the operation. You can access the object to be added from the Entity property of the EntityDataSourceChangingEventArgs object. If supplying a different object, the user is responsible for setting the correct entity type in the Entity property.
When you handle the exception in the event handler, set the ExceptionHandled property to true. This prevents the exception from being raised again. When you specify a value of false for the ExceptionHandled property, the EntityDataSource re-raises the exception.
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.