实体框架代码优先：按ID和类型映射多个实体

Question

namespace Sample.Orders
{
    public class Order : FullAuditedEntity<string>
    {
        [Column("OrderId")]
        public override string Id { get; set; }

        public long BillToAddressId { get; set; }
        public virtual Address.BillToAddress BillTo { get; set; }

        public string ShipToAddressId { get; set; }
        public virtual Address.ShipToAddress ShipTo { get; set; }
    }
}


namespace Sample.Shipments
{
    public class Shipmen : FullAuditedEntity<string>
    {
        [Column("ShipmentId")]
        public override string Id { get; set; }

        public long AddressId { get; set; }
        public virtual Address.ShipmentShipTo ShipTo { get; set; }
    }
}

namespace Sample.Address
{
    public abstract class Address : FullAuditedEntity<string>
    {
        public override string Id { get; set; }
        public double Name { get; set; }
        public string City { get; set; }

        public string ParentId { get; set; }
        public string AddressType { get; set; }
    }

    public class OrderBillTo : Address { }
    public class OrderShipTo : Address { }
    public class ShipmentShipTo : Address { }
}

数据库：

订购：

OrderId
BillToAddressId
ShipToAddressId

地址：

Id
Name
City
AddressType

如何像这样映射

OrderBill要通过以下字段从地址表中选择地址：ParentId = {OrderId}，AddressType ='OrderBillTo'

OrderShip要通过以下字段从地址表中选择地址：ParentId = {OrderId}，AddressType ='OrderShipTo'

ShipmentShip要通过以下字段从地址表中选择地址：ParentId = {AddressId}，AddressType ='ShipmentShipTo'

谢谢！

Answer 1

这不是EF旨在处理的用例。 它假定您在表和类之间具有一对一的映射。

也就是说，您真的需要所有Address的所有这些子类吗？

Answer 2

使用Fluent API：

modelBuilder
    .Entity<Order>
    .HasOptional(order => order.BillTo)
    .WithRequired(address => address.ParentId)
    .HasForeignKey(order.BillToAddressId);    

modelBuilder
    .Entity<Order>
    .HasOptional(order => order.ShipTo)
    .WithRequired(address => address.ParentId)
    .HasForeignKey(order.ShipToAddressId);    

modelBuilder
    .Entity<Shipment>
    .HasOptional(order => order.ShipmentShipTo)
    .WithRequired(address => address.ParentId)
    .HasForeignKey(order.AddressId);