ruby on rails - How do I stop circular "followers" in a model? -

basically, have table 2 columns, follower , followed. if user1 follows user2, need make sure user2 cannot follow user1. write in model validate that?

i have user model each 1 has id. created new relationship model, there 2 columns.

this i'm at.

class relationship < activerecord::base attr_accessible :followed_id, :follower_id  belongs_to :followed, class_name: "user" belongs_to :follower, class_name: "user"  validates :followed_id, presence: true validates :follower_id, presence: true validates :verify_no_circular_requirements  private   def verify_no_circular_requirements     return true   end end 

you write custom validator function:

for example(assumption, have followed_users method returns users current user following, , follow method, taking user id , "following user.):

class user < activerecord::base      has_many :users, inverse_of :user, as: followed_users     validates :verify_no_circular_followers      def followed        followed_users     end     def follow(user_id)       followed_users << user.find(user_id)    end     private       def verify_no_circular_followers           followed_users.each |u|              if u.index(self)                 return false              end           end           return true       end end