如何通过 has_many 关联迭代 ActiveRecord 关系

Question

所以我有某些冰淇淋，我想获得安大略省低脂冰淇淋和未过期冰淇淋的销售额。

冰淇淋有很多安大略省销售收据：

included_ice_cream = IceCream.produced_this_or_previous_month.where(low_fat: true, expired: false)

final_amount = included_ice_cream.ontario_sales_receipts.pluck(:number_of_buckets).sum * BUCKET_PRICE

但这会导致：

undefined method `ontario_sales_receipts' for #<IceCream::ActiveRecord_Relation:0x0055de80e3ffa8>

如何从 ActiveRecord 关系中获取 has_many 关联？

我最初可以查询 OntarioSaleRecept，但我不知道如何根据它们与特定 IceCream 的 has_one 关联来查询它们

included_ontario_sales_receipts = OntarioSalesReceipt.where( their associated IceCream is lowfat and non expired ... )

Answer 1

included_ice_cream = IceCream.produced_this_or_previous_month.where(
      low_fat: true,
      expired: false
    )
    total_amount = final_amount(included_ice_cream)

    def final_amount(included_ice_cream)
      included_ice_cream.map do |ice_cream|
        ice_cream.ontario_sales_receipts.pluck(:number_of_buckets).sum *
          BUCKET_PRICE
      end.sum
    end

这个怎么样？