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ObjectDataSourceObjectEventHandler Delegate

Represents the method that will handle the ObjectCreating and ObjectCreated events of the ObjectDataSource control.

Namespace:  System.Web.UI.WebControls
Assembly:  System.Web (in System.Web.dll)

'Declaration
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 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 'New


    Public Sub New(ByVal data As String) 
        _data = data

    End Sub 'New

    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


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, 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.
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