我正在尝试在EF中创建一个关系,其中外键是可选的。例如: https://stackoverflow.com/a/6023998/815553
我的问题是,有没有办法像上面这样做,但我可以将ContactID属性保留为模型的一部分?
在我的具体情况下,我有一个人和一张优惠券。人员表将具有可选的VoucherId,因为凭证仅在稍后阶段进入以链接到该人。
public class Person
{
public int ID { get; set; }
public string Name { get; set; }
public string Surname { get; set; }
public virtual Voucher Voucher { get; set; }
}
public class Voucher
{
public int ID { get; set; }
public string VoucherCode { get; set; }
}
modelBuilder.Entity<Person>()
.HasOptional(p => p.Voucher)
.WithOptionalDependent().Map(a => a.MapKey("VoucherId"));
我在这里有什么用,但我想要的是你在Person类中有VoucherId。为了向人员添加凭证,我必须将整个凭证对象提供给凭证参数。
using (DatabaseContext context = new DatabaseContext())
{
Voucher v = new Voucher()
{
VoucherCode = "23423"
};
context.Voucher.Add(v);
context.SaveChanges();
Person p = new Person()
{
Name = "Bob",
Surname = "Smith",
Voucher=v
};
context.Person.Add(p);
context.SaveChanges();
}
我希望能够做到:
Person p = new Person()
{
Name = "Bob",
Surname = "Smith",
VoucherId=v.ID // I wouldn't reference it like this, I would have the ID from a different source
};
答案 0 :(得分:2)
您可以像这样创建FK映射:
public class Person
{
public int ID { get; set; }
public string Name { get; set; }
public string Surname { get; set; }
[ForeignKey( "Voucher" )]
public int? VoucherId { get; set; }
public virtual Voucher Voucher { get; set; }
}