private void AddTable_OnClick(object sender, RoutedEventArgs e)
        {
            var proxy = new RestaurantServiceClient();
            var table = new Table
            {
                NoSeats      = Convert.ToInt32(TextBoxSeatsPerTable.Text),
                RestaurantId = Convert.ToInt32(HiddenResId.Content.ToString())
            };

            if (ValidateTable(table))
            {
                proxy.CreateTableAsync(table);
                ToTableDataGrid();
            }
            else
            {
                MessageBoxResult prompt =
                    MessageBox.Show("Please enter valid characters in all fields", "Invalid Input");
            }
        }