ObjectDataSourceObjectEventHandler Delegate
Represents the method that will handle the ObjectCreating and ObjectCreated events of the ObjectDataSource control.
Assembly: System.Web (in System.Web.dll)
Public Delegate Sub ObjectDataSourceObjectEventHandler ( sender As Object, e As ObjectDataSourceEventArgs )
Parameters
- sender
-
Type:
System.Object
The source of the event.
- e
-
Type:
System.Web.UI.WebControls.ObjectDataSourceEventArgs
An ObjectDataSourceEventArgs that contains the event data.
When you create an ObjectDataSourceObjectEventHandler delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate. For more information about event handler delegates, see NIB: Consuming Events.
The following code example demonstrates how to use an ObjectDataSource control with a business object and a GridView control to retrieve and display information. In this example, as in many real-world scenarios, it might not be possible or appropriate to use a default instance of the business object with the ObjectDataSource control. In this example, the ObjectDataSource cannot successfully call the default constructor because it will throw an exception. In some cases, the default constructor might be protected, and in others it might not initialize the business object to a desired state. Whatever the reason, you can instantiate the business object yourself and set the instance to the ObjectInstance property of the ObjectDataSourceEventArgs object that is passed to the handler. This is the business object instance that the ObjectDataSource will use to perform its work.
<%@ Import namespace="Samples.AspNet.VB" %> <%@ Page language="vb" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <script runat="server"> Private Sub NorthwindLogicCreating(sender As Object, e As ObjectDataSourceEventArgs) ' Create an instance of the business object using a non-default constructor. Dim eLogic As EmployeeLogic = New EmployeeLogic("Not created by the default constructor!") ' Set the ObjectInstance property so that the ObjectDataSource uses the created instance. e.ObjectInstance = eLogic End Sub ' NorthwindLogicCreating </script> <html xmlns="http://www.w3.org/1999/xhtml" > <head> <title>ObjectDataSource - VB Example</title> </head> <body> <form id="Form1" method="post" runat="server"> <asp:gridview id="GridView1" runat="server" datasourceid="ObjectDataSource1"> </asp:gridview> <asp:objectdatasource id="ObjectDataSource1" runat="server" selectmethod="GetAllEmployees" onobjectcreating="NorthwindLogicCreating" typename="Samples.AspNet.VB.EmployeeLogic" > </asp:objectdatasource> </form> </body> </html>
The following code example demonstrates the example basic business object used in the preceding example.
Imports System Imports System.Collections Imports System.Web.UI Imports System.Web.UI.WebControls Namespace Samples.AspNet.VB Public Class EmployeeLogic Public Sub New() Throw New NotSupportedException("Initialize data.") End Sub 'NewNew Public Sub New(ByVal data As String) _data = data End Sub 'NewNew Private _data As String ' Returns a collection of NorthwindEmployee objects. Public Function GetAllEmployees() As ICollection Dim al As New ArrayList() al.Add(_data) Return al End Function 'GetAllEmployees End Class 'EmployeeLogic End Namespace ' Samples.AspNet.VB
Available since 2.0