public IHttpActionResult GetParent(int id)
        {
            Parent parent = parentService.GetParent(id);

            if (parent == null)
            {
                return(NotFound());
            }
            return(Ok(parent));
        }
        public async Task <IActionResult> Index()
        {
            var user = await _userManager.GetUserAsync(User);

            var isParent = await _userManager.IsInRoleAsync(user, "Parent");

            var isStudent = await _userManager.IsInRoleAsync(user, "Student");

            var isTeacher = await _userManager.IsInRoleAsync(user, "Teacher");

            if (isStudent)
            {
                return(View(_gradeService.GetGrades(g => g.StudentId == user.Id)));
            }
            else if (isParent)
            {
                var students = _parentService.GetParent(s => s.Id == user.Id).Students;
                var grades   = _gradeService.GetGrades(
                    g => students.Any(
                        s => s.Id == g.StudentId
                        )
                    );

                return(View(grades));
            }
            else if (isTeacher)
            {
                return(RedirectToAction("AddGrade"));
            }
            else
            {
                return(View("Error"));
            }
        }