EF Core - Many to many relationship on a class

Question

User-Friend relationship

I find an answer

Entity Framework Core: many-to-many relationship with same entity and try like this.

Entitys:

Answer 1

The problem is that you can't have one collection to support both one-to-many associations. Friend has two foreign keys that both need an inverse end in the entity they refer to. So add another collection as inverse end of MainUser:

public class User
{
    public int UserId { get; set; }
    public virtual ICollection MainUserFriends { get; set; }
    public virtual ICollection Friends { get; set; }
}

And the mapping:

modelBuilder.Entity()
    .HasKey(f => new { f.MainUserId, f.FriendUserId });

modelBuilder.Entity()
    .HasOne(f => f.MainUser)
    .WithMany(mu => mu.MainUserFriends)
    .HasForeignKey(f => f.MainUserId).OnDelete(DeleteBehavior.Restrict);

modelBuilder.Entity()
    .HasOne(f => f.FriendUser)
    .WithMany(mu => mu.Friends)
    .HasForeignKey(f => f.FriendUserId);

One (or both) of the relationships should be without cascading delete to prevent multiple cascade paths.