Question

in this screencast Ryan Bates showed how to implement reputation system from scratch. But is there any way to give the current_user only 1 vote, and check whether user has already voted for application, and if yes, restrict the possibility of voting?

I think something like this in user.rb should work, but I don’t know ho to exactly write it

   def has_one_vote
      Restrict amount of user votes to 1
   end

Thanks

Answer 1

I’m assuming you have Users, Votes, and Posts, and that users vote on posts.

You should add a uniqueness validator to the Vote class on the user_id attribute, scoped to the post_id. This limits the number of votes a user can have on a given post to one:

class Vote
  belongs_to :user
  belongs_to :post

  validates :user_id, uniquness: { scope: :post_id }
end

---

To limit the total number of votes a user can ever create, either remove the scope from the uniqueness validator, or (more correctly) move the foreign key into the users table.

That is, either this:

class Vote
  belongs_to :user
  belongs_to :post
  validates :user_id, uniquness: true
end

or this:

class User
  belongs_to :vote
end