GridViewDeleteEventHandler Delegate
Assembly: System.Web (in system.web.dll)
'Declaration Public Delegate Sub GridViewDeleteEventHandler ( _ sender As Object, _ e As GridViewDeleteEventArgs _ ) 'Usage Dim instance As New GridViewDeleteEventHandler(AddressOf HandlerMethod)
/** @delegate */ public delegate void GridViewDeleteEventHandler ( Object sender, GridViewDeleteEventArgs e )
Not applicable.
Parameters
- sender
The source of the event.
- e
A GridViewDeleteEventArgs object that contains the event data.
The GridView control raises the RowDeleting event when a Delete button (a button with its CommandName property set to "Delete") is clicked, but before the GridView control deletes the record. This allows you to provide an event-handling method that performs a custom routine, such as canceling the delete operation, whenever this event occurs.
When you create a GridViewDeleteEventHandler 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 Events and Delegates.
The following example demonstrates how to programmatically add a GridViewDeleteEventHandler delegate to the RowDeleting event of a GridView control.
<%@ 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"> Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) ' Create a new GridView control. Dim customersGridView As New GridView() ' Set the GridView control's properties. customersGridView.ID = "CustomersGridView" customersGridView.DataSourceID = "CustomersSqlDataSource" customersGridView.AutoGenerateColumns = True customersGridView.AutoGenerateDeleteButton = True Dim keyArray() As String = {"CustomerID"} customersGridView.DataKeyNames = keyArray ' Programmatically register the event-handling methods. AddHandler customersGridView.RowDeleting, AddressOf CustomersGridView_RowDeleting ' Add the GridView object to the Controls collection ' of the PlaceHolder control. GridViewPlaceHolder.Controls.Add(customersGridView) End Sub Sub CustomersGridView_RowDeleting(ByVal sender As Object, ByVal e As GridViewDeleteEventArgs) ' User the sender parameter to retrieve the GridView control ' that raised the event. Dim customersGridView As GridView = CType(sender, GridView) ' Cancel the delete operation if the user attempts to remove ' the last record from the GridView control. If customersGridView.Rows.Count <= 1 Then e.Cancel = True Message.Text = "You must keep at least one record." End If End Sub </script> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server"> <title>GridViewDeleteEventHandler Example</title> </head> <body> <form id="form1" runat="server"> <h3>GridViewDeleteEventHandler Example</h3> <asp:label id="Message" forecolor="Red" runat="server"/> <br/> <asp:placeholder id="GridViewPlaceHolder" runat="server"/> <!-- This example uses Microsoft SQL Server and connects --> <!-- to the Northwind sample database. Use an ASP.NET --> <!-- expression to retrieve the connection string value --> <!-- from the Web.config file. --> <asp:sqldatasource id="CustomersSqlDataSource" selectcommand="Select [CustomerID], [CompanyName], [Address], [City], [PostalCode], [Country] From [Customers]" deletecommand="Delete from Customers where CustomerID = @CustomerID" connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>" runat="server"> </asp:sqldatasource> </form> </body> </html>
The following example demonstrates how to declaratively add a GridViewDeleteEventHandler delegate to the RowDeleting event of a GridView control.
<%@ 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"> Sub CustomersGridView_RowDeleting(ByVal sender As Object, ByVal e As GridViewDeleteEventArgs) ' Cancel the delete operation if the user attempts to remove ' the last record from the GridView control. If CustomersGridView.Rows.Count <= 1 Then e.Cancel = True Message.Text = "You must keep at least one record." End If End Sub </script> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server"> <title>GridView RowDeleting Example</title> </head> <body> <form id="form1" runat="server"> <h3>GridView RowDeleting Example</h3> <asp:label id="Message" forecolor="Red" runat="server"/> <br/> <!-- The GridView control automatically sets the columns --> <!-- specified in the datakeynames property as read-only. --> <!-- No input controls are rendered for these columns in --> <!-- edit mode. --> <asp:gridview id="CustomersGridView" datasourceid="CustomersSqlDataSource" autogeneratecolumns="true" autogeneratedeletebutton="true" datakeynames="CustomerID" onrowdeleting="CustomersGridView_RowDeleting" runat="server"> </asp:gridview> <!-- This example uses Microsoft SQL Server and connects --> <!-- to the Northwind sample database. Use an ASP.NET --> <!-- expression to retrieve the connection string value --> <!-- from the Web.config file. --> <asp:sqldatasource id="CustomersSqlDataSource" selectcommand="Select [CustomerID], [CompanyName], [Address], [City], [PostalCode], [Country] From [Customers]" deletecommand="Delete from Customers where CustomerID = @CustomerID" connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>" runat="server"> </asp:sqldatasource> </form> </body> </html>