public ExamViewModel(IEventAggregator eventAggregator)
{
this.eventAggregator = eventAggregator;
Exams = new ObservableCollection <Exam>(ServiceDataProvider.GetAllExams());
ServiceDataProvider.AddExamNotification += ServiceDataProvider_AddExamNotification;
eventAggregator.GetEvent <ExamPeriodEvent>().Subscribe(p => SubcribeToParentTableNameChange(p));
eventAggregator.GetEvent <CourseEvent>().Subscribe(p => SubcribeToParentTableNameChange(p));
}