public async Task <IActionResult> Edit(int id, StudentCourseEdit model)
{
if (id != model.Student.Id)
{
return(NotFound());
}
if (ModelState.IsValid)
{
try
{
_context.Update(model.Student);
await _context.SaveChangesAsync();
IEnumerable <int> listCourses = model.SelectedCourses;
IQueryable <Enrollment> toBeRemoved = _context.Enrollment.Where(s => !listCourses.Contains(s.CourseId) && s.StudentId == id);
_context.Enrollment.RemoveRange(toBeRemoved);
IEnumerable <int> existCourses = _context.Enrollment.Where(s => listCourses.Contains(s.CourseId) && s.StudentId == id).Select(s => s.CourseId);
IEnumerable <int> newCourses = listCourses.Where(s => !existCourses.Contains(s));
foreach (int courseId in newCourses)
{
_context.Enrollment.Add(new Enrollment {
CourseId = courseId, StudentId = id
});
}
await _context.SaveChangesAsync();
}
catch (DbUpdateConcurrencyException)
{
if (!StudentExists(model.Student.Id))
{
return(NotFound());
}
else
{
throw;
}
}
return(RedirectToAction(nameof(Index)));
}
return(View(model));
}
// GET: Students/Edit/5
public async Task <IActionResult> Edit(int?id)
{
if (id == null)
{
return(NotFound());
}
var student = _context.Student.Where(s => s.Id == id).Include(s => s.Courses).First();
if (student == null)
{
return(NotFound());
}
StudentCourseEdit viewModel = new StudentCourseEdit
{
Student = student,
CourseList = new MultiSelectList(_context.Course.OrderBy(s => s.Title), "Id", "Title"),
SelectedCourses = student.Courses.Select(sa => sa.CourseId)
};
return(View(viewModel));
}