public IHttpActionResult PostCustomBill(CustomBillModel customBillModel)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            var customBill = new CustomBill
            {
                BillName = customBillModel.BillName,
                EstimatedAmount = customBillModel.EstimatedAmount,
                UserId = customBillModel.UserId,
                WebsiteUrl = customBillModel.WebsiteUrl
            };

            db.CustomBills.Add(customBill);

            try
            {
                db.SaveChanges();
            }
            catch (DbUpdateException)
            {
                if (CustomBillExists(customBill.CustomBillId))
                {
                    return Conflict();
                }
                else
                {
                    throw;
                }
            }

            customBillModel.CustomBillId = customBill.CustomBillId;

            return Ok(customBillModel);
        }
        public IHttpActionResult PutCustomBill(int id, CustomBill customBill)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

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

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

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

            return StatusCode(HttpStatusCode.NoContent);
        }