我创建了 2 个代表数据库实体的类。
第一个实体:
public enum FlightStatus
{
checkIn,
gateClosed,
arrived,
departedAt,
unknown,
canceled,
expectedAt,
delayed,
InFlight
}
public class Flight
{
[Key]
public string FlightNumber { get; set; }
public DateTime Arrival { get; set; }
public DateTime Departure { get; set; }
public string CityOfArrival { get; set; }
public string CityOfDeparture { get; set; }
public char Terminal { get; set; }
public FlightStatus Status { get; set; }
public int Gate { get; set; }
public virtual ICollection<Passanger> PassengerList { get; set; }
public double PriceForFirstClass { get; set; }
public double PriceForBusiness { get; set; }
public double PriceForEconom { get; set; }
}
第二个实体:
public enum Sex
{
M,
F
}
public enum FlightClass
{
First,
Business,
Econom,
}
public enum TicketType
{
OneWay,
TwoWay,
}
public class Passenger
{
[Key]
public string Passport { get; set; }
public string flightNumber { get; set; }
[ForeignKey("flightNumber")]
public virtual Flight flight { get; set; }
public string FirstName { get; set; }
public string SecondName { get; set; }
public string Nationality { get; set; }
public DateTime DateOfbirthday { get; set; }
public Sex SexOfPassanger { get; set; }
public FlightClass ClassForPassanger { get; set; }
public TicketType TypeOfTicket { get; set; }
}
然后我创建了一个DbContext
:
class FlightsDatabase : DbContext
{
public DbSet<Flight> Flights { get; set; }
public DbSet<Flight> FlightsArchive { get; set; }
public DbSet<Passenger> Passengers { get; set; }
}
当我尝试使用这段代码时:
using (FlightsDatabase flights = new FlightsDatabase())
{
foreach (Flight flight in flights.Flights)
{
if (Math.Abs((flight.Departure - DateTime.Now).Days) <= 1)
{
timeCame(flight, null);
}
if (flight.Departure < DateTime.Now)
{
flightsToClean.Add(flight);
}
}
moveOldFlights(flightsToClean, null);
}
我收到这个错误
Multiple object sets per type are not supported. The object sets 'Flights' and 'FlightsArchive' can both contain instances of type 'Project_Airline_Info.Models.Flight'.
所以我的问题是如何在 DbContext 类中创建 2 个具有相同泛型类型的 DBset。
最佳答案
简短的回答是你不能这样做。考虑这行代码:
var flight = context.Set<Flight>().Where(f => f.FlightNumber == "123");
它如何知道使用哪个集合来获取数据?
可能最简单的解决方法是继承 Flight
类并将其用于您的其他 DbSet
:
public class ArchiveFlight : Flight
{
}
和你的上下文:
public class FlightsDatabase :DbContext
{
public DbSet<Flight> Flights { get; set; }
public DbSet<ArchiveFlight> FlightsArchive { get; set; }
public DbSet<Passanger> Passengers { get; set; }
}
这样做的好处是,您现在可以向存档的航类添加属性,例如存档日期:
public class ArchiveFlight : Flight
{
public DateTime DateArchived { get; set; }
}
关于c# - 如何首先在 Entity Framework 代码中创建 2 个相同类型的 dbsets?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/38640279/