Question

说我有Restaurant和Reservation型号。我想根据餐馆ID找到每家餐厅的预订，如下所示：

@reservations = Reservation.find( # current user )
@restaurants = []
@reservations.each do |res|
  @restaurants += Restaurant.where('id like ?', res.rest_id)
end

尝试此操作时，这会构造一个数组，我试图将其转换为Active Record对象，但是不成功。我错过了什么，还是有更明显的方法来做到这一点？

Answer 1

restaurant.rb

has_many :reservations

预订

belongs_to :restaurant, class_name: 'Restaurant', foreign_key: 'rest_id'

您可以找到此预订的餐馆记录

@reservation = Reservation.joins(:restaurant).where(id: reservation_id)

Answer 2

#load all reservations matching your condition, and eager-load all associated restaurants
@reservations = Reservation.where(<some condition>).includes(:restaurants)

#get all associated restaurants for all objects in the @reservations collection 
#which have been eager loaded, so this won't hit the db again), 
#flatten them to a single array, 
#then call `uniq` on this array to get rid of duplicates
@restaurants = @reservations.map(&:restaurants).flatten.uniq

编辑 - 添加了flatten，在评论中添加了解释

Rails：在has-many / belongs-to关联中查找匹配属性

2 个答案: