Active Record查询通过关系查找与Rails has_many中的所有条件匹配的记录

Question

我有两个模型，分别是Apartment和Amenities，它们通过ApartmentAmenities关联。 我正在尝试实现一个过滤器，在该过滤器中，我仅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

我有一个查询工作，它将返回所有至少匹配给定设施的设施之一的公寓，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，在放弃几天然后回到它上面之后，我终于找到了这个问题： 如何查找通过对象包含has_many的记录包含某个列表的所有对象的记录？

这使我想到了正确的答案：

  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