Occurs before the object that is identified by the TypeName property is discarded.
Assembly: System.Web (in System.Web.dll)
The event is always raised before the instance of the business object is discarded. If the business object implements the IDisposable interface, the Dispose method is called after this event is raised.
Handle the event to call other methods on the object, set properties, or perform clean-up that is specific to the object before the object is destroyed. A reference to the object is accessed by the ObjectInstance property, which is exposed by the ObjectDataSourceEventArgs object.
When you use a ObjectDataSource control with a LINQ to SQL class, you must cancel the disposing of the data-context class in an handler for the event. This step is necessary because LINQ to SQL supports deferred execution, whereas the ObjectDataSource control tries to dispose the data context after the Select operation.
For more information about how to handle events, see Consuming Events.
This section contains two code examples. The first code example demonstrates how to use an ObjectDataSource object with a business object and a GridView control to display information. The second code example provides the middle-tier business object that is used in the first code example.
The following code example demonstrates how to use an ObjectDataSource control with a business object and a GridView control to display information. You might work with a business object that is very expensive to create (in terms of time or resources) for every data operation your Web page performs. One way to work with an expensive object might be to create an instance of it once, and then cache it for subsequent operations instead of creating and destroying it for every data operation. This example demonstrates this pattern. You can handle the ObjectCreating event to check the cache for an object first, and only create an instance of it, if one is not already cached. Then, handle the event to cache the business object for future use, instead of destroying it. In this code example, the CancelEventArgs.Cancel property of the ObjectDataSourceDisposingEventArgs object is set to true to direct the ObjectDataSource to not call the Dispose method on the object.
The following code example provides the example middle-tier business object that the preceding code example uses. The code example consists of a basic business object, defined by the EmployeeLogic class, which is a stateful class that encapsulates business logic. For a complete working example, you must compile this code as a library and use these classes from an ASP.NET page (.aspx file).
The following example shows how to handle the event when using an ObjectDataSource control with a LINQ to SQL class.