Fluent API and One to One

Question

I am trying to relate an ApplicationRole (IdentityRole) to a Parent role as it's type of Role. I would like to understand the Fluent API a little better to accomplish this.

public class ApplicationRole : IdentityRole
{
    [StringLength(128)]
    [DisplayName("Based On Role")]
    public string BasedOnRoleId { get; set; }

    [ForeignKey("BasedOnRoleId")]
    public virtual ApplicationRole BasedOnRole { get; set; }
}

I currently have something like this that doesn't work...of course:

modelBuilder.Entity<ApplicationRole>()
                .HasKey(e => e.BasedOnRoleId)
                .HasRequired(e => e.BasedOnRole)
                .WithOptional(e => e.??)

Answer 1

See these answers:

Adding 0..1 relation in EF code first

EF 1 to 1..* relationship