in lib/helpers.rb [43:50]
def vote_for(obj)
raise ArgumentError, t(:user_id_is_required) unless user
raise ArgumentError, t(:value_is_required) unless params["value"]
raise ArgumentError, t(:value_is_invalid) unless %w[up down].include? params["value"]
user.vote(obj, params["value"].to_sym)
obj.reload.to_hash.to_json
end