Override the Delete Button Handler

One way to intercept record deletion in your generated application is to override the DeleteButton_Click() button handler method.
- Anh Trinh, Software Engineer, Iron Speed, Inc.

November 1, 2006
Iron Speed Designer V4.0

Override the Delete Button Handler

In some cases it is useful to intercept record deletions in your generated application. For example, suppose you do not want certain selected records to be deleted when your user clicks the "Delete" button? One way to accomplish this is to override the DeleteButton_Click() button handler method. In the example below, we check an order’s postal code when the user clicks the "Delete" button. If the postal code is "11111", then the deletion is cancelled and an error message is displayed; otherwise, the selected record is deleted.

Override the DeleteButton_Click() handler method in the OrdersTableControl class, located in:

.NET Framework 1.1:

...\<App Folder>\Orders\ShowOrdersTablePage.Controls.cs. or .vb

.NET Framework 2.0:

...\<App Folder>\App_Code\Orders\ShowOrdersTablePage.Controls.cs or .vb

C#:

public override void OrdersDeleteButton_Click(object sender, EventArgs args)
{
    try {
        DbUtils.StartTransaction();
        OrdersTableControlRow[] reclist = this.GetSelectedRecordControls();
        foreach (OrdersTableControlRow rec in reclist)
        {
           if (rec.ShipPostalCode.Text.Equals("11111"))
           {
                BaseClasses.Utils.MiscUtils.RegisterJScriptAlert(this, "Cannot delete record", "Cannot
                delete record");
                return;
           }
        }
        this.DeleteSelectedRecords(false);
        this.Page.CommitTransaction(sender);
        } catch (Exception ex) {
           BaseClasses.Utils.MiscUtils.RegisterJScriptAlert(this, "BUTTON_CLICK_MESSAGE",
           ex.Message);
           this.Page.RollBackTransaction(sender);
        } finally {
           DbUtils.EndTransaction();
        }
}

Visual Basic .NET:

Public Overrides Sub OrdersDeleteButton_Click(ByVal sender As Object, ByVal args As EventArgs)
    Try
        DbUtils.StartTransaction
        Dim reclist() As OrdersTableControlRow = Me.GetSelectedRecordControls
        For Each rec As OrdersTableControlRow In reclist
           If rec.ShipPostalCode.Text.Equals("11111") Then
                BaseClasses.Utils.MiscUtils.RegisterJScriptAlert(Me, "Cannot delete record", "Cannot
                delete record")
                Return
           End If
        Next
           Me.DeleteSelectedRecords(false)
           Me.Page.CommitTransaction(sender)
    Catch ex As Exception
        BaseClasses.Utils.MiscUtils.RegisterJScriptAlert(Me, "BUTTON_CLICK_MESSAGE",
        ex.Message)
        Me.Page.RollBackTransaction(sender)
    Finally
        DbUtils.EndTransaction
    End Try
End Sub

About the Author

Anh Trinh
Software Engineer, Iron Speed, Inc.

Anh is a software engineer at Iron Speed, Inc. He enjoys developing applications with Iron Speed Designer and Microsoft .NET technology.



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