一对一没有委托人，依赖EF？

Question

In this question (What does principal end of an association means in 1:1 relationship in Entity framework) the best answer says :

In one-to-one relation one end must be principal and second end must be dependent. Principal end is the one which will be inserted first and which can exist without the dependent one. Dependent end is the one which must be inserted after the principal because it has foreign key to the principal.

I wonder, how can I implement one-to-one relationship in Entity Framework where there are no principal and dependent elements? For example :

public class Person {
    public int Id {get;set;}
    public string Name {get;set;}
    public Person Spouse {get;set;}
}

Each person may or may not have another one as Spouse. If in one-to-one must sutisfy for the existence of principal and dependent elements, so, where in this Person model principal and where dependent ones?

Answer 1

As Gilad points out in the link that EF could not map one-to-one relationship to same table.

However, you can use the follow Code First Fluent API to simulate one-to-one relationship to same table. Under the hood, they behave the same way as you want.

public class Person
{
    public Person()
    {
        Dependents = new List<Person>();
    }

    public int Id { get; set; }
    public string Name { get; set; }
    public int Spouse { get; set; }
    public virtual ICollection<Person> Dependents { get; set; }
    public virtual Person Primary { get; set; }
}

public class PersonMap : EntityTypeConfiguration<Person>
{
    public PersonMap()
    {            
        HasRequired(t => t.Primary)
            .WithMany(t => t.Dependents)
            .HasForeignKey(d => d.Spouse);

    }
}