我创建了2个代表数据库实体的类。
第一实体:
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; }
}
当我尝试使用此代码时:
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);
}
我得到这个错误
每个类型不支持多个对象集。对象集“ Flights”和“ FlightsArchive”都可以包含“ Project_Airline_Info.Models.Flight”类型的实例。
因此,我的问题是如何在DbContext类中创建具有相同泛型的2个DBset。
简短的答案是您无法执行此操作。考虑以下代码行:
var flight = context.Set<Flight>().Where(f => f.FlightNumber == "123");
它如何知道要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
该类并将其用于您的其他类DbSet
:
public class ArchiveFlight : Flight
{
}
和您的上下文:
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,您现在可以将属性添加到已存档的排期中,例如存档日期:
public class ArchiveFlight : Flight
{
public DateTime DateArchived { get; set; }
}
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