public async Task <ActionResult <TheoryExam> > PostTheoryExam([FromForm] TheoryExam theoryExam)
        {
            var identity = User.Identity as System.Security.Claims.ClaimsIdentity;
            IEnumerable <System.Security.Claims.Claim> claims = identity.Claims;
            var national_code = claims.Where(p => p.Type == "national_code").FirstOrDefault()?.Value;

            var staff = _context.staffs.Where(q => q.national_code == national_code).FirstOrDefault();

            if (staff == null)
            {
                return(Unauthorized());
            }

            theoryExam.staff_id = staff.id;

            _context.theory_exams.Add(theoryExam);
            await _context.SaveChangesAsync();

            return(CreatedAtAction("GetTheoryExam", new { id = theoryExam.id }, theoryExam));
        }
        public async Task <IActionResult> PutTheoryExam(int id, [FromForm] TheoryExam theoryExam)
        {
            var identity = User.Identity as System.Security.Claims.ClaimsIdentity;
            IEnumerable <System.Security.Claims.Claim> claims = identity.Claims;
            var national_code = claims.Where(p => p.Type == "national_code").FirstOrDefault()?.Value;

            var staff = _context.staffs.Where(q => q.national_code == national_code).FirstOrDefault();

            if (staff == null)
            {
                return(Unauthorized());
            }

            theoryExam.staff_id = staff.id;

            if (id != theoryExam.id)
            {
                return(BadRequest());
            }

            theoryExam.updated_at            = DateTime.Now;
            _context.Entry(theoryExam).State = EntityState.Modified;

            try
            {
                await _context.SaveChangesAsync();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!TheoryExamExists(id))
                {
                    return(NotFound());
                }
                else
                {
                    throw;
                }
            }

            return(NoContent());
        }