IDENTITY_INSERT设置为OFF时，1：1映射并且无法为表'DivisionParticipant'中的Identity列插入显式值

Question

I needed a 1:1 mapping of DivisionParticipant and Team with both IDs being auto increment. I did this because we wanted to use to Nullable FK's, Team and Player . Before Team ID was the PK to DivisionParticipant ID , but now DivisionParticipant ID is auto increment and Team is now added as a property with the FK to get the 1:1 working. This works fine and minimal code changes were needed when we do a read, but now on a save we get this error below. The ID of DivisionParticipant was made to autoincrement so I am unsure what column it is speaking of?

Cannot insert explicit value for identity column in table 'DivisionParticipant' when IDENTITY_INSERT is set to OFF

Classes

public class DivisionParticipant
{
    public int Id {get; set;}
    public virtual Team Team { get; set; }
    public virtual Player Player { get; set; }
}

 public class Team 
{
    public int Id {get; set;}
    public virtual DivisionParticipant DivisionParticipant { get; set; }
}

DataContext

        modelBuilder.Entity<Team>()
        .HasOptional(t => t.DivisionParticipant)
        .WithRequired(t => t.Team);

Answer 1

EF6 doesn't support 1:1 relationships without the FK on the dependent side being the PK which means the PK on one side cannot use an identity. Check out this answer for the explanation from the EF Program Manager.