聚合多筆資料 - Rails 開發實踐

 1#language:zh-TW
 2# ...
 3場景: 假設 Aotoki 有兩筆 30 天的訂閱，可以看到 60 天後到期
 4    假設 會員 Aotoki 有一些訂閱紀錄
 5      | amount |
 6      | 30     |
 7      | 30     |
 8    當 我打開訂閱狀態頁面
 9    那麼 我會看到 2 次 "延展 30 天"
10    並且 我會看到 "60 天後到期"

 1# features/step_definitions/subscription.rb
 2
 3# ...
 4
 5Given('會員 {word} 有一些訂閱紀錄') do |name, table|
 6  user_id = @users[name]
 7
 8  Subscription.create(user_id: user_id, expired_at: 0.days.from_now)
 9  subscription = Subscription.by_user(user_id: user_id).first
10  table.hashes.each do |row|
11    subscription.extend_with(amount: row['amount'].to_i)
12  end
13  subscription.save!
14end
15
16# ...
17
18Then('我會看到 {int} 次 {string}') do |count, text|
19  expect(page).to have_text(text, count: count)
20end

 1class Subscription
 2  # ...
 3
 4  attribute :user_id, :integer
 5  attribute :expired_at, :datetime, default: -> { 30.days.from_now }
 6  attribute :items, array: true, default: -> { [] }
 7
 8  def expired_in_days
 9    (([0, expired_at - Time.zone.now].max + items.sum.days) / 1.day).ceil
10  end
11
12  def extend_with(amount:)
13    items << amount
14  end
15
16  # ...
17end

 1# app/controllers/subscriptions_controller.rb
 2
 3class SubscriptionsController < ApplicationController
 4  # ...
 5  def index
 6    @subscription = Subscription.by_user(user_id: current_user.id).first
 7
 8    # 移除 render plain: "..." 改為使用 View
 9    # render plain: "#{@subscription.expired_in_days} 天後到期"
10  end
11  # ...
12end

 1<!-- app/views/subscriptions/index.html.erb -->
 2<div><%= @subscription.expired_in_days %> 天後到期</div>
 3<table>
 4  <thead>
 5    <tr>
 6      <th>#</th>
 7      <th>天數</th>
 8    </tr>
 9  </thead>
10  <tbody>
11    <% @subscription.items.each_with_index do |item, idx| %>
12      <tr>
13        <td><%= idx %></td>
14        <td>延展 <%= item %> 天</td>
15      </tr>
16    <% end %>
17  </tbody>
18</table>