protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
 {
     base.OnNavigatedTo(e);
     int id = int.Parse(NavigationContext.QueryString["classroom"]);
     classroom = (from c in app.School.ClassRooms where c.Id == id select c).FirstOrDefault();
     this.DataContext = classroom;
 }
 public async void FillViewData(BasicClassRoom[] rooms)
 {
     await Task.Run(() =>
     {
         foreach (BasicClassRoom room in rooms)
         {
             _classRooms.AddOrUpdateKeyValue(room);
         }
     });
     NotifyPropertyChanged("ClassRooms");
 }