public IHttpActionResult PutPayment(int id, Payment payment)
        {
            if (!ModelState.IsValid)
            {
                return(BadRequest(ModelState));
            }

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

            db.Entry(payment).State = EntityState.Modified;

            try
            {
                db.SaveChanges();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!PaymentExists(id))
                {
                    return(NotFound());
                }
                else
                {
                    throw;
                }
            }

            return(StatusCode(HttpStatusCode.NoContent));
        }
        public void addDetail(int id)
        {
            PaymentEntities db = new PaymentEntities();

            var bill = db.Bill.Find(id);

            db.Entry(bill).State = EntityState.Modified;

            bill.Detail = Detail;
        }