// GET: Lesson
public ActionResult Index(int?SelectedCourse)
{
List <Course> courses = lessonB.CourseList();
ViewBag.SelectedCourse = new SelectList(courses, "CourseID", "Title", SelectedCourse);
int courseID = SelectedCourse.GetValueOrDefault();
return(View(lessonB.ListeFiltreLesson(SelectedCourse, courseID).ToList()));
}