Domain Driven Design Model - domain-driven-design

Question

I am building ParkingReservation in DDD, In short means that people can invite place and when the car get in the camera identify the model and update the status of the place.
I divided the model to three Bounded contexts:
The first is Reservation Context that include the following objects:
`public class Lot
{
public int ID { get; set; }
public string Name { get; set; }
public Address Address { get; set; }
public List<Place> Places { get; set; }
}
public class Place
{
public int ID { get; set; }
public int FloorNumber { get; set; }
public int RowNumber { get; set; }
public int ParkingNumber { get; set; }
}
public class Car
{
public int ID { get; set; }
public string Model { get; set; }
}
public class Driver
{
public int ID { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string UserName { get; set; }
public string Password { get; set; }
public int Age { get; set; }
public Gender Gender { get; set; }
public string Phone { get; set; }
public string Email { get; set; }
public bool AcceptAdsToMail { get; set; }
public byte[] PictureData { get; set; }
public DateTime RegistrationTime { get; set; }
public DriverStatuses DriverStatuses { get; set; }
}
public class Reservation
{
public int ID { get; set; }
public Driver Driver { get; set; }
public Car Car { get; set; }
public Place Place { get; set; }
public DateTime OrderTime { get; set; }
public DateTime ParkingStartTime { get; set; }
public DateTime ParkingEndTime { get; set; }
public ParkingStatuses ParkingStatus { get; set; }
}
public class ParkingHistory
{
public int ID { get; set; }
public Place Place { get; set; }
public Driver Driver { get; set; }
public Car Car { get; set; }
public DateTime StartTime { get; set; }
public DateTime EndTime { get; set; }
}`
The Parking Lot has list of places
the Driver reserve place through the application
the saved place saved in the Reservation object and when the parking time
elapsed, new parkinghistory added to parkinghistories list that belong to driver and car so you can watch history per car or driver.
for this context of Reservation:
(1) Is it correct to put Driver and Reservation for the Aggregate Roots? or maybe Lot too?
(2) Place is entity or value object?
Thank you

Answer 1

The main goal of your use case is scheduling. You need to think about a consistency boundary around that idea. To avoid time slots overlapping for a place in a lot you will need to create a new abstraction for the purpose.
"PlaceInLotReservations" sounds as a good option as an value object to serve as a factory for a Reservation aggregate. In order to represent reality of how scheduling works you should feed that aggregate in the context of a day, so "PlaceInLotReservationsRepository" should has a "findByDate" method that collects all Reservations for a place in a given datetime.
So the semantics would be something like:
val placeInLotReservations = PlaceInLotReservationsRepository.findBy(datetime)
val reservation = placeInLotReservations.reserveFor(car, driver, startingTime, endingTime)
ReservationsRepository.save(reservation)
If there are lot of reservations in a place and so race conditions you can even make the VO smaller by passing in day quarters instead of a day for the initial look up.
BTW, can and driver are VOs in the context of the Reservation aggregate (they are not aggregates).
You can also have the history by querying the Reservation repository, you don´t need ParkingHistory.
Hope it helps.