Adminアカウントで売上を見れるようにする【いせ日記】

$rails c
2.5.3 :001 >Admin.last.products.joins(:purchase_record_products)
 => #<ActiveRecord::AssociationRelation [#<Product id: 1, admin_id: 1, user_id: nil, name: "test1", description: "これはテスト1用の商品です。", price: 1000, created_at: "2020-10-10 10:14:37", updated_at: "2020-10-10 10:14:37", image: "alvin-mahmudov-vKuEhorbvYI-unsplash__1_.jpg">, #<Product id: 1, admin_id: 1, user_id: nil, name: "test1", description: "これはテスト1用の商品です。", price: 1000, created_at: "2020-10-10 10:14:37", updated_at: "2020-10-10 10:14:37", image: "alvin-mahmudov-vKuEhorbvYI-unsplash__1_.jpg">,

class Admin < ApplicationRecord
  devise :database_authenticatable,
         :recoverable, :rememberable, :validatable
  has_many :products, dependent: :destroy
  
  def sales
  end
  
  def sales_one_month
  end 
  
end

  def sales
    sold_products = self.products.joins(:purchase_record_products)
    sold_products.sum(:price)
  end

where(created_at: Time.now.all_month)

モデル名.joins(:関連名).where(結合先のテーブル名: { カラム名: 値 })

  def sales_one_month
    sold_products = products.joins(:purchase_record_products).where({ purchase_record_products: {created_at: Time.now.all_month} })
    sold_products.sum(:price)
  end 

$ rails c 
2.5.3 :001 > Admin.last.sales
  Admin Load (0.3ms)  SELECT  `admins`.* FROM `admins` ORDER BY `admins`.`id` DESC LIMIT 1
   (0.2ms)  SELECT SUM(`products`.`price`) FROM `products` INNER JOIN `purchase_record_products` ON `purchase_record_products`.`product_id` = `products`.`id` WHERE `products`.`admin_id` = 1
 => 14000
2.5.3 :002 > Admin.last.sales_one_month
  Admin Load (0.7ms)  SELECT  `admins`.* FROM `admins` ORDER BY `admins`.`id` DESC LIMIT 1
   (0.3ms)  SELECT SUM(`products`.`price`) FROM `products` INNER JOIN `purchase_record_products` ON `purchase_record_products`.`product_id` = `products`.`id` WHERE `products`.`admin_id` = 1 AND `purchase_record_products`.`created_at` BETWEEN '2020-10-01 00:00:00' AND '2020-10-31 23:59:59'
 => 14000 

<div class="container">
  <h2 class="text-center">Adminトップページ</h2>
  　<ul class="list-group list-unstyled">
        <li class="admin-sales-all d-flex justify-content-between border">
          <p>今までの売上  <span><%=current_admin.sales.to_s %>円</span></p>
          <a class="p-0 m-0"><%=link_to '詳細', admins_sales_record_path, class: "btn btn-success"%></a>
        </li>
        <li class="admin-sales-one-month d-flex justify-content-between border">
          <p>今月の売上   <span><%=current_admin.sales_one_month.to_s %>円</span></p>
          <a><%=link_to '詳細', admins_sales_record_path, class: "btn btn-success"%></a>
      </li>
    </ul>
   </h2>
</div>

 resource :sales_record, only: [:show]

class Admins::SalesRecordsController < Admins::ApplicationController
    def show
    end
end

has_many :purchase_record_products, through: :products

<table class="table">
    <thead>
        <tr>
            <th>商品名</th>
            <th>価格</th>
            <th>購入日</th>
        </tr>
    </thead>
    <tbody>
      <% @purchase_record_products.each do |prd| %>
        <% product = prd.product %>
        <tr>
            <td><%=product.name %></td>
            <td><%=product.price %>円</td>
            <td><%=product.created_at %></td>
        </tr>
      <% end %>
    </tbody>
</table>

@purchase_record_products = current_admin.purchase_record_products.preload(:product)