mysql - 事件记录 has_many

Question

我需要列出所有用户及其销售的产品总量及其电子邮件和产品总量，

class User < ActiveRecord::Base
  # id, location_id, email
  has_many :orders, dependent: :destroy
end

class Order < ActiveRecord::Base
#status, payment_mode, total_cost, user_id
  has_many  :order_items, dependent: :destroy
  belongs_to :user
end

class OrderItem < ActiveRecord::Base
# order_id, product_id, quantity,total_price
  belongs_to :order
  belongs_to :product
end

User
id email
1  test@gmail.com
2  test2@gmail.com

订单 用户 ID 1 1 2 2

OrderItem
id order_id product_id  quantity 
1  1        1            5
2  1        2            5
2  2        3            5

我需要显示如下 名称 产品数量 测试@gmail.com 10 test1@gmail.com 5

Answer 1

请尝试这个:

OrderItem.includes(:order => :user).group('users.email').sum(:quantity)