friendship.rb

class Friend < ActiveRecord::Base

 belongs_to :user
 belongs_to :contact, :class_name => "User", :foreign_key => "contact_id"

 # user befriends contact
 def self.befriend(user,contact)
    relationship = find_by_user_id_and_contact_id(user.id,friend.id)
    if relationship.nil?
      transaction do
        Friend.create(:user => user, :contact => contact)
      end
    end
 end

end

class User < ActiveRecord::Base 
  
  has_many :friends, :dependent => :destroy
  has_many :contacts, :through => :friends, :order => "created_at DESC", :dependent => :destroy

end