public async Task <ActionResult> PostBills(ApiBills bills)
        {
            try
            {
                var resource = new CoreBills
                {
                    BillId    = bills.BillId,
                    BillLate  = bills.BillLate,
                    BillName  = bills.BillName,
                    BillPrice = bills.BillPrice,
                    DueDate   = bills.DueDate,
                    User      = await _userRepo.GetUserById(bills.UserId)
                };

                await _repo.AddBillAsync(resource);

                return(Ok("Bill had been added!"));
            }
            catch (Exception e)
            {
                return(BadRequest($"Something went wrong. {e.Message}"));
            }
        }