sql - Active Record查询通过关系在Rails has_many中查找符合所有条件的记录

Question

我有两个模型，Apartments 和 Amenities，它们通过 ApartmentAmenities 关联。我正在尝试实现一个过滤器，只显示具有所有指定便利设施的公寓。

class Amenity < ActiveRecord::Base  
  has_many :apartment_amenities
  has_many :apartments, through: :apartment_amenities
end

class ApartmentAmenity < ActiveRecord::Base
  belongs_to :apartment
  belongs_to :amenity
end

class Apartment < ActiveRecord::Base
  has_many :apartment_amenities
  has_many :amenities, through: :apartment_amenities
end

我有一个正在运行的查询，它将返回至少匹配给定集合中的一项便利设施的所有公寓，如下所示:

Apartment.joins(:apartment_amenities).where('apartment_amenities.amenity_id IN (?)', [1,2,3])

但这不是我想要的。

Answer 1

好吧，放弃了几天又重新开始，我终于找到了这个问题:How to find records, whose has_many through objects include all objects of some list?

这让我得到了正确的答案:

  def self.with_amenities(amenity_ids)
    where("NOT EXISTS (SELECT * FROM amenities
      WHERE NOT EXISTS (SELECT * FROM apartment_amenities
        WHERE apartment_amenities.amenity_id = amenities.id
        AND apartment_amenities.apartment_id = apartments.id)
      AND amenities.id IN (?))", amenity_ids)
  end