public IResult CheckPayment(CreditCard creditCard) { var result = _paymentDal.Get(c => c.CardNumber == creditCard.CardNumber); if (result != null) { result.CardBalance = result.CardBalance - creditCard.CardBalance; if (result.CardBalance < 0) { return(new ErrorResult("Yeterli bakiye bulunmamaktadır.")); } _paymentDal.CheckPayment(result); return(new SuccessResult()); } return(new ErrorResult("Kart bulunamadı")); }