Question

I am developing an application based on questions and answers, and I would like to prevent a registered user from posting multiple answers to the same question.

How can I do that? And where is the best place to put this code (i.e. controller, model)?

Answer 1

I finally wrote this code:

# Reply model
validates_uniqueness_of :user_id, :scope => :question_id

# Helper method
def user_has_replied(user, question)
  Reply.find( :first, :conditions => {:user_id => user.id, :question_id => question.id} )
end