void CustomerEditorForm_UpdateAsync(object sender, DataActionEventArgs e)
        {
            CustomerAdapter ca = CreateAdapter <CustomerAdapter>();

            if (!ca.ExistsWithCode(GetEditorData <Customer>()))
            {
                ca.Update(GetEditorData <Customer>());
            }
            else
            {
                e.Cancelled   = true;
                e.UserMessage = "An other customer with the specified code already exists.";
            }
        }