按日期统计订单中特定系列的已售产品

Question

我正在尝试找出在给定日期范围内按特定家庭的订单计算已售产品的最佳方法。

这些是我的简化模型：

• Orderplaced_on
• OrderItemorder_id、product_id、金额
• Productfamily_id
• Family

所以，现在给定一些日期，比如d1 和d2，我需要计算给定Family 中有多少Product 在这些Order 中。

想要的输出应该是这样的：

# all these are products from the same family sold in the last week
[
  {"product_24": 3435},
  {"product_34": 566},
  {"product_83": 422}
  …
]

我知道如何循环所有订单，但我认为应该有更好的方法。

Answer 1

假设您的数据模型和变量应该是这样的：

OrderItem.joins(:order)
         .joins(product: :family)
         .where(orders: {created_at: d1..d2})
         .where(products: {family_id: <YOUR_FAMILY_ID>})
         .group(:product_id)
         .sum(:amount)

这将生成以下sql：

SELECT
    SUM("order_items"."amount") AS sum_amount,
    "order_items"."product_id" AS order_items_product_id
FROM "order_items"
    INNER JOIN "orders" ON "orders"."id" = "order_items"."order_id"
    INNER JOIN "products" ON "products"."id" = "order_items"."product_id" 
    INNER JOIN "families" ON "families"."id" = "products"."family_id" 
WHERE
    ("orders"."created_at" BETWEEN ? AND ?)
        AND "products"."family_id" = ?
GROUP BY "order_items"."product_id"

并返回以下结构：

=> [{product_id => <sum of this product id since d1 until d2 for family_id>}, ...]

另外，我假设您想对每种产品的数量求和。让我知道是否适合您。

Answer 2

class CreateOrders < ActiveRecord::Migration[5.1]
  def change
    create_table :orders do |t|
      t.timestamps
    end
  end
end

class CreateOrderItems < ActiveRecord::Migration[5.1]
  def change
    create_table :order_items do |t|
      t.integer :order_id, index:true
      t.integer :product_id, index:true
      t.integer :amount
      t.timestamps
    end
  end
end

class CreateProducts < ActiveRecord::Migration[5.1]
  def change
    create_table :products do |t|
      t.text :name
      t.integer :family_id, index:true
      t.timestamps
    end
  end
end

class CreateFamilies < ActiveRecord::Migration[5.1]
  def change
    create_table :families do |t|
      t.text :name
      t.timestamps
    end
  end
end

class Family < ApplicationRecord
  has_many :products
end

class Order < ApplicationRecord
  has_many :order_items
  has_many :products, through: :order_items
end

class OrderItem < ApplicationRecord
  belongs_to :order
  belongs_to :product
end

class Product < ApplicationRecord
  belongs_to :family
  has_many :order_items
end

irb(main):015:0> Order.joins(:order_items).joins(:products).where("products.family_id":2).where("orders.created_at": [(Time.now).to_date..(Time.now + 1.day).to_date]).count
   (0.6ms)  SELECT COUNT(*) FROM "orders" INNER JOIN "order_items" ON "order_items"."order_id" = "orders"."id" INNER JOIN "order_items" "order_items_orders_join" ON "order_items_orders_join"."order_id" = "orders"."id" INNER JOIN "products" ON "products"."id" = "order_items_orders_join"."product_id" WHERE "products"."family_id" = ? AND ("orders"."created_at" BETWEEN '2018-04-20' AND '2018-04-21')  [["family_id", 2]]
=> 3

Answer 3

不是完整的答案，因为您已经有两个非常详细的答案 - 但有一些注释

我会设置范围...因为我们不确定您的数据库是否垂直...另外，请避免任何时间范围问题，确保您在将混乱输入查询之前得到一整天。这些只是示例，没有经过语法检查或推荐的最佳形式

  # ensure we are getting whole of each day
  full_d1 = d1.beginning_of_day
  full_d2 = d2.end_of_day

  #  change the order based on whatever you have more of
  scope :orders -> {where(created_at: full_d1..full_d2)}
  scope :family -> {where(product: family_id)}

  # use something like - swap order based on db conditions
  Order.orders.family  # ... then add the rest of what they are throwing down or .size / .count

此外，正如 S/O 中其他地方所述，您可以缓存 has_many 关系的计数 - link