private void AddPassengerButton_Click(object sender, RoutedEventArgs e) { StringBuilder errors = new StringBuilder(); if (string.IsNullOrWhiteSpace(outboundTickets.Firstname)) { errors.AppendLine("Enter the firstname!"); } if (string.IsNullOrWhiteSpace(outboundTickets.Firstname)) { errors.AppendLine("Enter the lastname!"); } if (string.IsNullOrWhiteSpace(outboundTickets.Phone)) { errors.AppendLine("Enter the phone!"); } if (CountryComboBox.SelectedItem == null) { errors.AppendLine("Enter the country!"); } if (PhoneText.Text.Length > 14) { errors.AppendLine("Invalid phone number!"); } if (errors.Length > 0) { MessageBox.Show(errors.ToString(), "Error!", MessageBoxButton.OK, MessageBoxImage.Error); return; } outboundTickets.BookingReference = BookRefGen(); outboundTickets.PassportCountryID = ((Countries)CountryComboBox.SelectedItem).ID; Tickets tickets = new Tickets(); tickets = (Tickets)outboundTickets.Clone(); if (returnTickets.Schedules != null) { var returnTickets = (Tickets)outboundTickets.Clone(); returnTickets.Schedules = this.returnTickets.Schedules; returnTickets.Schedules.ID = this.returnTickets.Schedules.ID; ticketsList.Add(returnTickets); } ticketsList.Add(tickets); TicketsData.Items.Add(tickets); }