ruby-on-rails - Rails 3 : Arel for NOT EXISTS?

Question

您如何在Arel中编写NOT EXISTS？我在将查询转换为Arel时遇到麻烦:

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，用奇怪的名字，因为我不知道如何为我不知道的域名命名。

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)