Rails - 与 ActiveRecord 的深度嵌套连接

Question

我偶尔需要在我的应用程序中执行跨多个表的联接，但还没有完全弄清楚如何对超过 3 个表执行此操作：

class Store < ApplicationRecord
  has_many :products
end

class Product < ApplicationRecord
  belongs_to :store
  has_many :product_variants
end

class ProductVariant < ApplicationRecord
  belongs_to :product
  has_many :order_list_items
end

class OrderListItem < ApplicationRecord
  belongs_to :product_variant
  has_many :consumers
end

class Consumer < ApplicationRecord
  belongs_to :order_list_item
end

目前我已准备就绪：

Store.joins(products: [{ product_variants: :order_list_items }])

我现在想做的是加入属于 OrderListItem 的每个消费者。

但是，当我尝试以下操作时：

Store.joins(products: [{ product_variants: :order_list_items }], order_list_items: [:consumers])

我收到错误：

(Object doesn't support #inspect)

以下两次尝试同样的错误：

Store.joins(products: [{ product_variants: :order_list_items }, order_list_items: [:consumers]])

Store.joins(products: [{ product_variants: :order_list_items }], order_list_items: [:consumers])

我已正确设置关联，order_list_item.consumers 和 consumer.order_list_items 和 order_list_item.product_variant 以及 product_variant.order_list_items 工作正常。

我也没有在任何模型上覆盖 initialize。

工作 SQL 看起来像这样：

SELECT stores.id, products.id as product_id, product_variants.id as product_variant_id, order_list_items.id as list_item_id, consumers.id as consumer_id
FROM stores
INNER JOIN products ON products.store_id = stores.id
INNER JOIN product_variants on product_variants.product_id = products.id
INNER JOIN order_list_items on order_list_items.product_variant_id = product_variants.id
INNER JOIN consumers on consumers.order_list_item_id = order_list_items.id;

感谢任何提示。

Answer 1

试试这个

Store.joins(products: [product_variants: [order_list_items: :consumers]])

下面是sql查询

SELECT "stores".* FROM "stores" 
INNER JOIN "products" 
ON "products"."store_id" = "stores"."id" 
INNER JOIN "product_variants" 
ON "product_variants"."product_id" = "products"."id" 
INNER JOIN "order_list_items" 
ON "order_list_items"."product_variant_id" = "product_variants"."id" 
INNER JOIN "consumers" 
ON "consumers"."order_list_item_id" = "order_list_items"."id";

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