public Tournament_Management()
        {
            InitializeComponent();
            List <TournamentPers> allTournaments =
                TMPersistenz.GetAllTournaments(ApplicationState.GetValue <Client>("LoggedOnUser").Username);

            dg_tournament_list.ItemsSource = allTournaments;
        }
 private void b_delete_tournament_Click(object sender, RoutedEventArgs e)
 {
     if (ApplicationState.GetValue <TournamentPers>("CurrentTournament") != null)
     {
         TMPersistenz.DeleteTournamentInDB(ApplicationState.GetValue <TournamentPers>("CurrentTournament").Name);
         dg_tournament_list.ItemsSource = null;
         ApplicationState.SetValue("CurrentTournament", null);
         l_current_tournament.Content = "";
         List <TournamentPers> allTournaments =
             TMPersistenz.GetAllTournaments(ApplicationState.GetValue <Client>("LoggedOnUser").Username);
         dg_tournament_list.ItemsSource = allTournaments;
     }
     else
     {
         MessageBox.Show("Bitte zuerst ein Turnier auswählen!", "KICKERCUP", MessageBoxButton.OK,
                         MessageBoxImage.Error);
     }
 }