ruby-on-rails - 使用 join with has_many :through relationship 获取记录

Question

我有一个 Hotel 模型和 HotelAmenity 模型和 Amenity 模型，它们通过 has_many :through 相关，例如这个:

class Hotel < ActiveRecord::Base
    has_many :hotel_amenities, :dependent => :destroy
    has_many :amenities, through: :hotel_amenities
end

class Amenity < ActiveRecord::Base
    has_many :hotel_amenities, :dependent => :destroy
    has_many :hotels, through: :hotel_amenities
end


class HotelAmenity < ActiveRecord::Base
  belongs_to :amenity
  belongs_to :hotel
end

现在我的操作中有 hotel_id，我想获取所有设施 [1,2,3] 这是 array 的 amenity_id。

Answer 1

好问题!!别担心，您可以使用 Hotel Model 上的 join 来解决这个问题:首先，您将通过 hotel_id

找到酒店

@hotel= Hotel.find_by_id(params[:user_id))

现在你可以找到带有amenity_array [1,2,3]的酒店

 @hotels = @hotels.joins(:hotel_amenities).where(hotel_amenities: { amenity_id: [1,2,3] }) // this can returns a hotel two or more time


@hotels = @hotels.joins(:hotel_amenities).where(hotel_amenities: { amenity_id: [1,2,3] }).uniq // this will return all hotels without redundant records 

希望这对你有用。