app/models/party_comment.rb
class PartyComment < ActiveRecord::Base
belongs_to :party
belongs_to :issue
belongs_to :parliament_period
attr_accessible :body, :party_id, :issue_id, :party, :issue, :parliament_period_id
validates_uniqueness_of :party_id, scope: [:issue_id, :parliament_period_id]
validates_presence_of :party, :issue, :parliament_period
end