private void btnAcceptOngoingBookingRequest_Click(object sender, RoutedEventArgs e)
 {
     try
     {
         OngoingBooking oB = dtgRequestedOngoingBookings.SelectedItem as OngoingBooking;
         oBHandler.AcceptOngoingBookingRequest(oB.Id, admin.Id);
         dtgRequestedOngoingBookings.SelectedItem = null;
         dtgRequestedOngoingBookings.ItemsSource  = oBHandler.GetAllPendingOngoingBookings();
     }
     catch (ArgumentNullException)
     {
         MessageBox.Show("You need to select a booking to accept it.");
     }
 }
        public AdminWindow(Admin admin)
        {
            InitializeComponent();
            this.admin      = admin;
            oBHandler       = new OngoingBookingsHandler();
            sBHandler       = new SingleBookingsHandler();
            companyHandler  = new CompanyHandler();
            activityHandler = new ActivitiesHandler();

            dtgRequestedOngoingBookings.ItemsSource = oBHandler.GetAllPendingOngoingBookings();
            dtgRequestedSingleBookings.ItemsSource  = sBHandler.GetAllPendingSingleBookings();
            sections = new int[6] {
                1, 2, 3, 4, 5, 6
            };
            cboNewActivitySectionsRequired.ItemsSource = sections;
        }