相关疑难解决方法(0)

我试图在Ruby on Rails项目中执行以下操作:

class FoodItem < ActiveRecord::Base
  has_and_belongs_to_many :food_categories
  has_many :places, :through => :food_categories
end

class FoodCategory < ActiveRecord::Base
  has_and_belongs_to_many :food_items
  belongs_to :place
end

class Place < ActiveRecord::Base  
  has_many :food_categories
  has_many :food_items, :through => :food_category
end

但调用实例方法some_food_item.places会给我以下错误:

ActiveRecord::StatementInvalid: PGError: ERROR:  column 
food_categories.food_item_id does not exist
LINE 1: ...laces".id = "food_categories".place_id    WHERE (("food_cate...

: SELECT "places".* FROM "places"  INNER JOIN "food_categories" ON "places".id = "food_categories".place_id    WHERE (("food_categories".food_item_id = 1))

这很有道理 - 因为FoodItem和FoodCategory上的HABTM我有一个名为的映射表food_categories_food_items.

我有什么做的就是some_food_item.places要正确对待地方了通过映射表,而不是寻找一个food_item_id在 …