Rails 3:Arel for NOT EXISTS？

Question

你怎么写NOT EXISTSArel？我在将此查询转换为Arel时遇到问题:

SELECT * FROM deals 
WHERE NOT EXISTS (
   SELECT 1 FROM reward_deals 
   WHERE reward_deals.deal_id = deal.id 
   AND NOT (
      reward_deals.awarding_type = 'deal' 
      AND reward_deals.deal_id = reward_deals.awarding_id
   )
 )

Answer 1

这是答案,名字很奇怪,因为我不知道如何给出一个对我不熟悉的域名.

deals = Deal.arel_table
reward_deals = RewardDeal.arel_table
awarding_condition= reward_deals[:awarding_type].eq('deal')\
                                .and(reward_deals[:deal_id]\
                                       .eq(reward_deals[:awarding_id]))

reward_deals_condition= reward_deals[:deal_id].eq(deals[:id])\
                              .and(awarding_condition.not)
Deal.where(RewardDeal.where(reward_deals_condition).exists.not)