public AppointmentEntity(List <TimeDuration> timeDurations , CustomerEntity customer, List <Pet> pets, PaymentMethod paymentMethod) { Durations = timeDurations; Customer = customer; Payment = new Payment(Service.Price, new Price { Currency = Currency.UsDollars, Value = (Service.Price.Value * .25m) }, customer.Debit, paymentMethod); Customer.AddPayment(Payment); Pets = pets; AppointmentInstances = new List <AppointmentInstance>(); foreach (var duration in Durations) { var instance = new AppointmentInstance { Date = duration.StartDateTime, AppointmentStatus = AppointmentStatus.Awaiting }; } }