How should I model friendships between users with EF code first?

Question

I\'m tring to figure out how to represent friendships between users with Entity Framework (5) Code First. My initial idea was to create a class Friendship which contains ref

Answer 1

I managed to find a similar question on SO after some more googling, and there's a solution there that at least made it into the database without problems.

Basically, I added foreign keys per user to the Friendship class, made them a composite primary key and configured the second foreign key not to cascade on delete. I ended up using EF fluent configuration.

public class Friendship
{
    public virtual int UserId1 { get; set; }
    public virtual int UserId2 { get; set; }
    public virtual User User1 { get; set; }
    public virtual User User2 { get; set; }
    public DateTime since;
}

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    ...
    modelBuilder.Entity<Friendship>().HasKey(f => new { f.UserId1, f.UserId2 });
    modelBuilder.Entity<Friendship>()
      .HasRequired(f => f.User1)
      .WithMany()
      .HasForeignKey(f => f.UserId1);
    modelBuilder.Entity<Friendship>()
        .HasRequired(f => f.User2)
        .WithMany()
        .HasForeignKey(f => f.UserId2)
        .WillCascadeOnDelete(false);
}

Answer 2

You could define the foreign keys yourself or remove cascade delete, depending on your scenario. See this related question : Entity Framework Code First: FOREIGN KEY constraint may cause cycles or multiple cascade paths