public async Task <IActionResult> StudentCourseEditPost(int?id, string[] selectedCourses)
{
if (id == null)//method called with form which accepts hidden ID
{
return(NotFound());
}
//get provided user (from id)
Student student = await _context.Students
.Include(i => i.Enrollments)
.ThenInclude(i => i.Course)
.SingleOrDefaultAsync(m => m.Id == id);
//comparing user and person who calls this action
var user = await _userManager.FindByNameAsync(User.Identity.Name);
if (student.Id != user.Id)
{
return(RedirectToAction("AccessDenied", "Account"));
}
if (selectedCourses != null)
{
if (ModelState.IsValid)
{
//creat empty list for entities
student.Enrollments = new List <Enrollment>();
var selectedCoursesHS = new HashSet <string>(selectedCourses);
var studentEnrollments = new HashSet <int>
(student.Enrollments.Select(c => c.Course.CourseID));
//loop to add/remove courses
foreach (var course in _context.Courses)
{
if (selectedCoursesHS.Contains(course.CourseID.ToString()))
{
if (!studentEnrollments.Contains(course.CourseID))
{
student.Enrollments.Add(new Enrollment {
SmID = student.Id, CourseID = course.CourseID
});
}
}
else
{
if (studentEnrollments.Contains(course.CourseID))
{
Enrollment courseToRemove = student.Enrollments.SingleOrDefault(i => i.CourseID == course.CourseID);
_context.Remove(courseToRemove);
}
}
}
var result = await TryUpdateModelAsync <Student>(student, "", di => di.Enrollments);
try
{
await _context.SaveChangesAsync();
}
catch (DbUpdateException /* ex */)
{
//Log the error (uncomment ex variable name and write a log.)
ModelState.AddModelError("", "Unable to save changes. " +
"Try again, and if the problem persists, " +
"see your system administrator.");
}
}
}
return(RedirectToAction("StudentIndex"));
}
public ActionResult Navigation(int id)
{
Enrollment enroll = db.Enrollments.Find(id);
return(View(enroll));
}
