One to One Relationship with Different Primary Key in EF 6.1 Code First

Question

I am having an issue getting a reference to the employee object from the PayGroup object using Entity Framework 6.1. I have a foreign key in the database on PayGroup.Supervi

Answer 1

one-to-one relationship with explicit FK property (like your PayGroup.SupervisorId) is not supported.

So remove that property from the model:

public class PayGroup
{
    public int Id { get; set; }
    public virtual Employee Supervisor { get; set; }
}

and use the following fluent mapping:

modelBuilder.Entity()
    .HasRequired(e => e.Supervisor)
    .WithOptional()
    .Map(m => m.MapKey("SupervisorId"));

The WithOptional() call specifies two things. First that there is no inverse navigation property in Employee class, and second that the FK is optional (Allow Nulls = true in the table).

If you decide to add inverse navigation property

public class Employee
{
    public string EmployeeId { get; set; }
    public string FullName { get; set; }
    public virtual PayGroup PayGroup { get; set; } // <=
}

change it to WithOptional(e => e.PayGroup).

If you want to make it required (Allow Nulls = false in the table), then use the corresponding WithRequiredDependent overload (Dependent here means that the Employee will be the principal and PayGroup will be the dependent).