public async Task <IActionResult> Edit(int id, StudentsInCourseVM viewmodel)
{
if (id != viewmodel.Course.Id)
{
return(NotFound());
}
if (ModelState.IsValid)
{
try
{
_context.Update(viewmodel.Course);
await _context.SaveChangesAsync();
IEnumerable <int> listStudents = viewmodel.SelectedStudents;
IQueryable <Enrollment> toBeRemoved = _context.Enrollment.Where
(s => !listStudents.Contains(s.StudentId) && s.CourseId == id);
_context.Enrollment.RemoveRange(toBeRemoved);
IEnumerable <int> existStudents = _context.Enrollment
.Where(s => listStudents.Contains(s.StudentId) && s.CourseId == id).Select(s => s.StudentId);
IEnumerable <int> newStudents = listStudents.Where(s => !existStudents.Contains(s));
foreach (int studentID in newStudents)
{
_context.Enrollment.Add(new Enrollment {
StudentId = studentID, CourseId = id
});
}
await _context.SaveChangesAsync();
}
catch (DbUpdateConcurrencyException)
{
if (!CourseExists(viewmodel.Course.Id))
{
return(NotFound());
}
else
{
throw;
}
}
return(RedirectToAction(nameof(Index)));
}
ViewData["FirstTeacherID"] = new SelectList(_context.Set <Teacher>(), "Id", "FullName", viewmodel.Course.FirstTeacherID);
ViewData["SecondTeacherID"] = new SelectList(_context.Set <Teacher>(), "Id", "FullName", viewmodel.Course.SecondTeacherID);
return(View(viewmodel));
}
// GET: Courses/Edit/5
public async Task <IActionResult> Edit(int?id)
{
if (id == null)
{
return(NotFound());
}
var course = _context.Course.Where(m => m.Id == id).Include(m => m.Students).First();
if (course == null)
{
return(NotFound());
}
StudentsInCourseVM viewmodel = new StudentsInCourseVM
{
Course = course,
StudentList = new MultiSelectList(_context.Student.OrderBy(s => s.StudentId), "Id", "FullName"),
SelectedStudents = course.Students.Select(sa => sa.StudentId)
};
ViewData["FirstTeacherID"] = new SelectList(_context.Set <Teacher>(), "Id", "FullName", course.FirstTeacherID);
ViewData["SecondTeacherID"] = new SelectList(_context.Set <Teacher>(), "Id", "FullName", course.SecondTeacherID);
return(View(viewmodel));
}
