Question

I have Person and Course Entities With multiple relationships:

public class Course
{
    public int CourseID { get; set; }
    public virtual Person Leader { get; set; }
    public virtual ICollection<Person> Teachers { get; set; }
    public virtual Person CreatedBy { get; set; }
    public virtual Person UpdatedBy { get; set; }
    ...
}

public class Person
{
    public int PersonID { get; set; }
    public virtual ICollection<Course> CoursesCreated { get; set; }
    public virtual ICollection<Course> CoursesUpdated { get; set; }
    public virtual ICollection<Course> CoursesLead { get; set; }
    public virtual ICollection<Course> CoursesTutored { get; set; }
    ...
}

I have the following mapping:

modelBuilder.Entity<Course>().HasMany(x => x.Tutors)
                           .WithMany(p => p.CoursesTutored)
                           .Map(x =>
                               {
                                   x.MapLeftKey("PersonID");
                                   x.MapRightKey("CourseID");
                                   x.ToTable("Course_Tutors");
                               });

This works in that it sets up the Course_Tutors table as well as providing the course table with Leader_PersonID, CreatedBy_PersonID and UpdatedBy_PersonID.

However it also creates three extra Person columns in the course table: Person_PersonID1, Person_PersonID2, Person_PersonID3.

Can someone tell me how to get rid of these? I am assuming my mapping needs some more work.

Answer 1

Code First has problems identifying relationships by conversions when you have more than one relationship between two entities. You need to explicitly configure them.

modelBuilder.Entity<Course>()
     .HasRequired(c => c.Leader)
     .WithMany(p => p.CoursesLead)
     .Map(m => m.MapKey("Leader_PersonID"));

modelBuilder.Entity<Course>()
     .HasRequired(c => c.CreatedBy)
     .WithMany(p => p.CoursesCreated)
     .Map(m => m.MapKey("CreatedBy_PersonID"));

modelBuilder.Entity<Course>()
     .HasRequired(c => c.UpdatedBy)
     .WithMany(p => p.CoursesUpdated)
     .Map(m => m.MapKey("UpdatedBy_PersonID"));