ORM：友谊/佛教徒的关系

I'm trying to use ORM for the first time, I've defined the models like this:

User model:

class User extends Eloquent
{
    public function friends()
    {
       return $this->has_many_and_belongs_to('User', 'friends', 'user1_id', 'user2_id');
    }    
}

Friend model:

class Friend extends Eloquent
{
    public function friend()
    {
        return $this->belongs_to('User', 'user_id');
    }    
}

Friends mysql table:

id (pkey) # user1_id (references users.user_id) # user2_id (references users.user_id)

Right now by using $user->friends I get a unilateral list because the friends database parameters could be in any order (user1 is friend of user2 OR user2 is friend of user1). This would be ok if I was trying to use following/followers approach, but I want it to be reciprocal.

What is the best way to do this kinda of stuff? Inserting duplicated user1/user2 and user2/user1 on the database doesn't sound like a good approach and I wouldn't even know how to translate this to the ORM. Also, it seems the Friend model is not being used/getting called at all.

I'm also going to have a similar problem on the invite friend system.

You are looking for a Many to Many relationship, between Users! Check out how you can do this in Doctrine: Doctrine - Many to Many Self Referencing. Doctrine example might help you to get started.

The idea is that you have one Entity, Users, and they can be friends with each other.