public void LoadTeachers()
{
_teachers = new ObservableCollection <TeacherViewModel>(
dbContext.Teachers.Select(t => TeacherViewModel.FromTeacher(t)).ToList());
PropertyChanged.Invoke(this, new PropertyChangedEventArgs(nameof(Teachers)));
}
public void AddTeacher(Teacher teacher)
{
_teachers.Add(TeacherViewModel.FromTeacher(teacher));
PropertyChanged.Invoke(this, new PropertyChangedEventArgs(nameof(Teachers)));
}