public ActionResult Create(Instructor instructor)
        {
            if (ModelState.IsValid) {
                db.Instructors.Add(instructor);
                db.SaveChanges();
                return RedirectToAction("Index");
            }

            ViewBag.PersonID = new SelectList(db.OfficeAssignments, "PersonID", "Location", instructor.PersonID);
            return View(instructor);
        }
        private void UpdateInstructorCourses(string[] selectedCourses, Instructor instructorToUpdate)
        {
            if (selectedCourses == null) {
                instructorToUpdate.Courses = new List<Course>();
                return;
            }

            var selectedCoursesHS = new HashSet<string>(selectedCourses);
            var instructorCourses = new HashSet<int>
                (instructorToUpdate.Courses.Select(c => c.CourseID));
            foreach (var course in db.Courses) {
                if (selectedCoursesHS.Contains(course.CourseID.ToString())) {
                    if (!instructorCourses.Contains(course.CourseID)) {
                        instructorToUpdate.Courses.Add(course);
                    }
                } else {
                    if (instructorCourses.Contains(course.CourseID)) {
                        instructorToUpdate.Courses.Remove(course);
                    }
                }
            }
        }
 private void PopulateAssignedCourseData(Instructor instructor)
 {
     var allCourses = db.Courses;
     var instructorCourses = new HashSet<int>(instructor.Courses.Select(c => c.CourseID));
     var viewModel = new List<AssignedCourseData>();
     foreach (var course in allCourses) {
         viewModel.Add(new AssignedCourseData {
             CourseID = course.CourseID,
             Title = course.Title,
             Assigned = instructorCourses.Contains(course.CourseID)
         });
     }
     ViewBag.Courses = viewModel;
 }