EF 7 (Beta 7) 一对一关系

Question

I've noticed questions that have answered this problem for earlier beta versions of EF 7 (like here ), but I haven't seen it solved for Beta 7, so here it goes:

I have 2 entities, simplified as follows:

public class FirstEntity
{
    public int FirstEntityID { get; set; }
    /*
        Other fields here
    */
    public int? SecondEntityID { get; set; }
    public SecondEntity SecondEntityProperty { get; set; }
}

public class SecondEntity
{
    public int FirstEntityID { get; set; } 
    /*
        Other fields here
    */
    public FirstEntity FirstEntityProperty { get; set; }
}

The way to map everything has changed so much from earlier versions. How do I map these two entities in a One-to-One relationship?

Answer 1

It has been changed for EF7 rc1-final.

modelBuilder.Entity<FirstEntity>()
            .HasOne(q => q.SecondEntity)
            .WithMany()
            .HasForeignKey(q => q.SecondEntityID);

upd:

modelBuilder.Entity<FirstEntity>()
            .HasOne(q => q.SecondEntity)
            .WithOne(v => v.FirstEntity)
            .HasForeignKey<FirstEntity>(q => q.SecondEntityID);

Answer 2

Beta 7 relies heavily on using the Reference method of the Fluent API in order to do any kind of Foreign Key relationship, which has you first select the navigation property involved in the FK relationship. Then, since this is a One-to-One relationship, you use the InverseReference relationship to specify which navigation property on the other side of the relationship this would apply to. Only then can you actually start to specify the keys involved, using the ForeignKey and PrincipalKey methods.

All told, here's the solution that I used:

modelBuilder.Entity<SecondEntity>
    .Reference(s => s.FirstEntity)
    .InverseReference(f => f.SecondEntity)
    .ForeignKey(typeof(SecondEntity), "FirstEntityID")
    .PrincipalKey(typeof(FirstEntity), "SecondEntityID");