Many-To-Many Relationship in Code-First EF4

Question

How do you represent a many-to-many relationship in the EF4 Code-First CTP3?

For example if I have the following classes:

class User
{
    public int         


        

Answer 1

With many to many relationships you should include navigation properties on both sides and make them virtual (to utilize lazy loading)

class User
{
  public int Id { get; set; }
  public string Name { get; set; }
  public virtual ICollection Profiles { get; set; }
}

class Profile
{
  public int Id { get; set; }
  public string Name { get; set; }
  public virtual ICollection Users { get; set; }
}

Then with that setup you can define your many to many relationship (you can also let entity framework do it for you but I don't like the naming conventions it uses.)

        modelBuilder.Entity().
            HasMany(p => p.Users).
            WithMany(g => g.Profiles).
            Map(t => t.MapLeftKey("ProfileID")
                .MapRightKey("UserID")
                .ToTable("UserProfiles"));

This will give you a table named UserProfiles with UserID and ProfileID as Keys.