ruby-on-rails – Rails – 根据另一个表验证唯一性

我有投票和投票表格的帖子.我可以在投票和投票模型中验证唯一性,以确保用户不能多次投票或投票.我想验证这两个模型的唯一性,以便用户不能投票选出他们已经投票的帖子,反之亦然.香港专业教育学院尝试过自定义验证,userfaved,定义如下,但它不起作用.

class Vote < ActiveRecord::Base

 validates_uniqueness_of :user_id,:scope => :article_id #allows only one vote

 validate :userfaved

 def userfaved
  if Votedown.where( :user_id => :user_id,:artcle_id => :article_id).any?
      errors.add(:user_id,'already voted on this') 
  end
 end



class Votedown < ActiveRecord::Base

validates_uniqueness_of :user_id,:scope => :article_id #allows only one votedown

validate :userfaved

def userfaved
    if Vote.where(:user_id=> :user_id,:article_id => :article_id).any?
        errors.add(:user_id,'already voted on this')
    end
end

Votedown.where( :user_id => self.user_id,:article_id => self.article_id).any?