Rails 3联接2所属表

Question

我有以下架构：

class Locale < ActiveRecord::Base
  has_many :shops

  # region : String
end

class Shop < ActiveRecord::Base
  belongs_to :locale
  has_many :carts

  scope :europe, joins(:locale).where('locales.region = ?', 'Europe')
end

class Cart < ActiveRecord::Base
  belongs_to :shop

  scope :purchased, where('purchased_at is not null')

  # purchased_at : DateTime
end

我想查找在某个地区购买的所有购物车，我有几个作用域设置，以使查询更具可读性，但是在尝试时：

Cart.purchased.join（：shop）.merge（Shop.europe）

我收到错误消息：ActiveRecord :: ConfigurationError：未找到名为“ locale”的关联； 也许您拼错了？

关于如何进行这项工作有任何想法吗？

Answer 1

class Locale < ActiveRecord::Base
  has_many :shops

  scope :europe, where(region: 'Europe')
end

class Shop < ActiveRecord::Base
  belongs_to :locale
  has_many :carts
end


class Cart < ActiveRecord::Base
  belongs_to :shop

  scope :purchased, where('purchased_at is not null')
end

Cart.purchased.joins(shop: :locale).merge(Locale.europe)