活动记录has_many

Question

我需要列出所有用户以及他们通过电子邮件销售的产品总数以及产品总数，

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ID user_id 1 1 2 2

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

我需要显示类似名称product_count test@gmail.com 10 test1@gmail.com 5

Answer 1

请尝试以下方法：

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