Occurs when a Delete operation has completed.
Assembly: System.Web (in System.Web.dll)
Handle the event to examine the values of a return value or output parameters, or to determine whether an exception was thrown after a Delete operation has completed. The return value, output parameters, and exception handling properties are available from the ObjectDataSourceStatusEventArgs object that is associated with the event.
You can use the AffectedRows property of the ObjectDataSourceStatusEventArgs object to return the number of rows that were deleted from the Delete method. To do this, set the AffectedRows property. If you return the number of deleted rows from the method that is specified by the DeleteMethod property, the value is available from the ReturnValue property of the ObjectDataSourceStatusEventArgs object.
For more information about handling 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 delete data. The second code example shows the EmployeeLogic class 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 delete data. Initially, the GridView control displays a set of all employees, using the method that is specified by the SelectMethod property to retrieve the data from the EmployeeLogic object. Because the AutoGenerateDeleteButton property is set to true, the GridView control automatically displays a Delete button.
If you click the Delete button, the delete operation is performed using the method that is specified by the DeleteMethod property and any parameters that are specified in the DeleteParameters collection. In this code example, some preprocessing and post-processing steps are also performed. The NorthwindEmployeeDeleting delegate is called to handle the Deleting event before the operation is performed and the NorthwindEmployeeDeleted delegate is called to handle the event after the operation has completed to perform exception handling. In this code example, if a NorthwindDataException is thrown, it is handled by the NorthwindEmployeeDeleted method.
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB" Assembly="Samples.AspNet.VB" %> <%@ 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"> ' Called before a Delete operation. Private Sub NorthwindEmployeeDeleting(ByVal source As Object, ByVal e As ObjectDataSourceMethodEventArgs) ' The GridView passes the ID of the employee ' to be deleted. However, the business object, EmployeeLogic, ' requires a NorthwindEmployee parameter, named "ne". Create ' it now and add it to the parameters collection. Dim paramsFromPage As IDictionary = e.InputParameters If Not paramsFromPage("EmpID") Is Nothing Then Dim ne As New NorthwindEmployee(paramsFromPage("EmpID").ToString()) ' Remove the old EmpID parameter. paramsFromPage.Clear() paramsFromPage.Add("ne", ne) End If End Sub ' NorthwindEmployeeDeleting ' Called after a Delete operation. Private Sub NorthwindEmployeeDeleted(ByVal source As Object, ByVal e As ObjectDataSourceStatusEventArgs) ' Handle the Exception if it is a NorthwindDataException. If Not e.Exception Is Nothing Then ' Handle the specific exception type. The ObjectDataSource wraps ' any Exceptions in a TargetInvokationException wrapper, so ' check the InnerException property for the expected Exception types. If e.Exception.InnerException.GetType().Equals(GetType(NorthwindDataException)) Then Label1.Text = e.Exception.InnerException.Message ' Because the exception is handled, there is ' no reason to throw it. e.ExceptionHandled = True End If End If End Sub ' NorthwindEmployeeDeleted </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" autogeneratedeletebutton="true" autogeneratecolumns="false" datakeynames="EmpID"> <columns> <asp:boundfield headertext="EmpID" datafield="EmpID" /> <asp:boundfield headertext="First Name" datafield="FirstName" /> <asp:boundfield headertext="Last Name" datafield="LastName" /> </columns> </asp:gridview> <asp:objectdatasource id="ObjectDataSource1" runat="server" selectmethod="GetAllEmployees" deletemethod="DeleteEmployee" ondeleting="NorthwindEmployeeDeleting" ondeleted="NorthwindEmployeeDeleted" typename="Samples.AspNet.VB.EmployeeLogic"> <deleteparameters> <asp:parameter name="EmpID" type="Int32" /> </deleteparameters> </asp:objectdatasource> <asp:label id="Label1" runat="server" /> </form> </body> </html>
The following code example shows the EmployeeLogic class that is used in the preceding code example.
Imports System Imports System.Collections Imports System.Configuration Imports System.Data Imports System.Data.SqlClient Imports System.Web.UI Imports System.Web.UI.WebControls Namespace Samples.AspNet.VB ' ' EmployeeLogic is a stateless business object that encapsulates ' the operations you can perform on a NorthwindEmployee object. Public Class EmployeeLogic ' Return a collection of NorthwindEmployee objects. Public Shared Function GetAllEmployees() As ICollection Dim al As New ArrayList() ' Use the SqlDataSource class to wrap the ' ADO.NET code required to query the database. Dim cts As ConnectionStringSettings = ConfigurationManager.ConnectionStrings("NorthwindConnection") Dim sds As New SqlDataSource(cts.ConnectionString, _ "SELECT EmployeeID FROM Employees") Try Dim IDs As IEnumerable = sds.Select(DataSourceSelectArguments.Empty) ' Iterate through the Enumeration and create a ' NorthwindEmployee object for each ID. Dim enumerator As IEnumerator = IDs.GetEnumerator() While enumerator.MoveNext() ' The IEnumerable contains DataRowView objects. Dim row As DataRowView = CType(enumerator.Current,DataRowView) Dim id As String = row("EmployeeID").ToString() Dim nwe As New NorthwindEmployee(id) ' Add the NorthwindEmployee object to the collection. al.Add(nwe) End While Finally ' If anything strange happens, clean up. sds.Dispose() End Try Return al End Function 'GetAllEmployees Public Shared Function GetEmployee(anID As Object) As NorthwindEmployee Return New NorthwindEmployee(anID) End Function 'GetEmployee Public Shared Sub DeleteEmployee(ne As NorthwindEmployee) Dim retval As Boolean = ne.Delete() If Not retval Then Throw New NorthwindDataException("Employee delete failed.") End If ' Delete the object in memory. ne = Nothing End Sub 'DeleteEmployee Public Shared Sub DeleteEmployeeByID(anID As Integer) Dim tempEmp As New NorthwindEmployee(anID) DeleteEmployee(tempEmp) End Sub 'DeleteEmployeeByID End Class 'EmployeeLogic Public Class NorthwindEmployee Public Sub New() ID = DBNull.Value aLastName = "" aFirstName = "" End Sub 'New Public Sub New(anID As Object) Me.ID = anID Dim cts As ConnectionStringSettings = ConfigurationManager.ConnectionStrings("NorthwindConnection") Dim conn As New SqlConnection(cts.ConnectionString) Dim sc As New SqlCommand(" SELECT FirstName,LastName " & _ " FROM Employees " & _ " WHERE EmployeeID = @empId", conn) ' Add the employee ID parameter and set its value. sc.Parameters.Add(New SqlParameter("@empId", SqlDbType.Int)).Value = Int32.Parse(anID.ToString()) Dim sdr As SqlDataReader = Nothing Try conn.Open() sdr = sc.ExecuteReader() ' This is not a while loop. It only loops once. If Not (sdr Is Nothing) AndAlso sdr.Read() Then ' The IEnumerable contains DataRowView objects. Me.aFirstName = sdr("FirstName").ToString() Me.aLastName = sdr("LastName").ToString() Else Throw New NorthwindDataException("Data not loaded for employee id.") End If Finally Try If Not (sdr Is Nothing) Then sdr.Close() End If conn.Close() Catch se As SqlException ' Log an event in the Application Event Log. Throw End Try End Try End Sub 'New Private ID As Object Public ReadOnly Property EmpID() As Object Get Return ID End Get End Property Private aLastName As String Public Property LastName() As String Get Return aLastName End Get Set aLastName = value End Set End Property Private aFirstName As String Public Property FirstName() As String Get Return aFirstName End Get Set aFirstName = value End Set End Property Public Function Delete() As Boolean If ID.Equals(DBNull.Value) Then ' The Employee object is not persisted. Return True Else ' The Employee object is persisted. ' Use the SqlDataSource control as a convenient wrapper for ' the ADO.NET code needed to delete a record from the database. Dim cts As ConnectionStringSettings = ConfigurationManager.ConnectionStrings("NorthwindConnection") Dim sds As New SqlDataSource() Try sds.ConnectionString = cts.ConnectionString sds.DeleteParameters.Add(New Parameter("empID", TypeCode.Int32, Me.ID.ToString())) sds.DeleteCommand = "DELETE FROM [Order Details] " & _ "WHERE OrderID IN (SELECT OrderID FROM Orders WHERE EmployeeID=@empID)" sds.Delete() sds.DeleteCommand = "DELETE FROM Orders WHERE EmployeeID=@empID" sds.Delete() sds.DeleteCommand = "DELETE FROM EmployeeTerritories WHERE EmployeeID=@empID" sds.Delete() sds.DeleteCommand = "DELETE FROM Employees WHERE EmployeeID=@empID" sds.Delete() Return True Finally ' Clean up resources. sds.Dispose() End Try End If End Function 'Delete End Class 'NorthwindEmployee Public Class NorthwindDataException Inherits Exception Public Sub New(msg As String) MyBase.New(msg) End Sub 'New End Class 'NorthwindDataException End Namespace
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.