Rails：分组和显示与 3 个模型的关联的最佳方式

Question

我有 3 个模型：Place、Service、ItemService 和 ItemServicesProduction。

class Place < ActiveRecord::Base
  has_many :item_services, through: :place_item_services
  has_many :place_item_services
end


class Service < ActiveRecord::Base
  has_many: item_services
end


class ItemService < ActiveRecord::Base
  belongs_to :service
end

我想按服务显示 item_services 组的地点。 例如。

Table 地点_item_services

+----+----------+------------------+---------------------+---------------------+
| id | place_id | item_service_id  | created_at          | updated_at          |
+----+----------+------------------+---------------------+---------------------+
|  1 |        5 |                1 | 2016-05-16 12:31:59 | 2016-05-16 12:31:59 |
|  2 |        5 |                2 | 2016-05-16 12:31:59 | 2016-05-16 12:31:59 |
|  3 |        6 |                2 | 2016-05-21 07:58:19 | 2016-05-21 07:58:19 |
|  4 |        5 |                5 | 2016-06-02 08:32:24 | 2016-06-02 08:32:24 |
|  5 |        5 |                6 | 2016-06-02 08:32:24 | 2016-06-02 08:32:24 |
+----+----------+------------------+---------------------+---------------------+

table 服务

+----+-----------+
| id | name      |
+----+-----------+
|  1 | service 1 |
|  2 | service 2 |
+----+-----------+

table item_services

+----+-------+-------------+
| id | name  | facility_id |
+----+-------+-------------+
|  1 | sv1-1 |           1 |
|  2 | sv1-2 |           1 |
|  3 | sv1-3 |           1 |
|  4 | sv2-1 |           2 |
|  5 | sv2-2 |           2 |
|  6 | sv2-3 |           2 |
+----+------ +-------------+

当我在视图中显示地点时（地点 ID = 5） 我想显示

Place_Name
/*Service is here*/

 1. service 1
    - sv1-1
    - sv1-2
 2. service 2
    - sv2-2
    - sv2-3

最好的方法如何显示同上？ （可以使用 inclues、joins、group by .etc..）

Answer 1

你的控制器

@place    = Place.find(5)
@services = Services.includes({item_services: :place_item_services}).where(place_item_services: {place_id: @place.id})

您的看法

<p>Place: <%= @place.name %></p>
<ol>
  <% @services.each do |service| %>
    <li>
      <ul>
        <% service.item_services.each do |item_service| %>
          <li><%= item_service.name %></li>
        <% end %>
      </ul>
    </li>
  <% end %>
</ol>