public void BindClassesComboxData()
 {
     var list = new StudentContext().Classes.ToList();
     cbbClass.DataSource = list;
     cbbClass.DisplayMember = "Name";
     cbbClass.ValueMember = "Id";
 }
 public AddStudent(Student stu,StudentContext context)
 {
     InitializeComponent();
     BindClassesComboxData();
     this.stu = stu;
     this.context = context;
 }