C# Nested Linq Group By - linq

Question

I'd like to achive this output, ONE VIEWMODEL INSTANCE for each customer
CUSTOMER
TUI
DATE
PASSENGERS
VESSEL
01/05/2021
2
MORNING STAR
01/05/2021
7
CAPTAIN JOHN
01/05/2021
10
CAPTAIN JOHN
VESSEL
PASSENGERS
CAPTAIN JOHN
17
MORNING STAR
2
TOTAL
19
This is the model
public class Reservation {
public string Date { get; set; }
public string Destination { get; set; }
public string Customer { get; set; }
public string Vessel { get; set; }
public int TotalPersons { get; set; }
}
This is the view model so far
public class ReservationVM {
public string Customer { get; set; }
public List<Reservation> Reservations { get; set; }
}
So far, I can only create the list with the customer and the reservations
CUSTOMER
TUI
DATE
PASSENGERS
VESSEL
01/05/2021
2
MORNING STAR
01/05/2021
7
CAPTAIN JOHN
01/05/2021
10
CAPTAIN JOHN
Code
public IEnumerable<ReservationVM> Get() {
var result = dbContext.Reservations
.Where(x => x.Date == "2021-05-01")
.AsEnumerable()
.GroupBy(x => x.Customer)
.Select(x => new ReservationVM {
Customer = x.Key,
Reservations = x.ToList()
})
.OrderBy(x => x.Customer);
return result;
}
How could I include the part that displays the total passengers for each vessel?
VESSEL
PASSENGERS
CAPTAIN JOHN
17
MORNING STAR
2
TOTAL
19

Answer 1

The Total field must be at the level of ReservationVM (unless you want a vessel named Total, which you don't). Also, you should create another class, let's call it VesselReservationVm. You can do something as follows:
Classes:
public class Reservation {
public string Date { get; set; }
public string Customer { get; set; }
public string Vessel { get; set; }
public int TotalPersons { get; set; }
}
public class ReservationVM {
public string Customer { get; set; }
public List<Reservation> Reservations { get; set; }
public List<VesselReservationVM> VesselReservations { get; set; }
public int Total { get; set; }
}
public class VesselReservationVM {
public string Vessel { get; set; }
public int Passengers { get; set; }
}
Methods:
public IEnumerable<ReservationVM> GetCustomersReservations() {
var result = dbContext.Reservations
.Where(x => x.Date == "2021-05-01")
.AsEnumerable()
.GroupBy(x => x.Customer)
.Select(x => new ReservationVM {
Customer = x.Key,
Reservations = x.ToList(),
VesselReservations = GetCustomerVessels(x.ToList()),
Total = x.Select(r => r.TotalPersons).Sum()
})
.OrderBy(x => x.Customer);
return result;
}
public List<VesselReservationVM> GetCustomerVessels(
List<Reservation> reservations) {
var result = reservations
.GroupBy(r => r.Vessel)
.Select(g => new VesselReservationVM
{
Vessel = g.Key,
Passengers = g.Select(r => r.TotalPersons).Sum(),
})
.ToList();
return result;
}