so , you should also update the line:

User.find(1).friends

with:

User.find(1).friends << another_user

(sorry for the “spam”)

class User :friendships

As for your sql error, your model-defined relations seem a little hard to follow. Maybe you need something like this?

class User
has_many :friends, :through => 'friendships'
end

class Friendship
has_one :user
has_one :friend, :class_name => 'User', :foreign_key => 'friend_id'
end

of course, it is always nice to have some sort of validation and/or before_create/before_validation that makes sure if you are someone’s friend that they are also your friend. Or maybe you could walk a fine semantic line by pretending that one-way friendships are indications of an outstanding friend request (then delete the one-way upon rejecting, allowing the requester to later reiterate his request).