在belongs_to 关系中按父项排序active_admin 列

Question

我有两个模型：show_request 和 show。一个show_Request 属于一个show 和一个show has_many show_requests。在active_admin 的show_request 页面上，我想通过show 的created_at 值订购show_requests。到目前为止，这是我的代码：

ActiveAdmin.register ShowRequest do

  controller do
    def scoped_collection
      end_of_association_chain.includes(:show)
      #I also tried ShowRequest.includes(:show)
    end
  end

  index do
    column 'Show', sortable: "shows.created_at_asc" do |show_req|
        link_to show_req.show.name, admin_show_path(show_req.show)
    end
  end

end

这里是服务器日志：

Started GET "/admin/show_requests" for 127.0.0.1 at 2015-09-18 09:35:36 -0400
Processing by Admin::ShowRequestsController#index as HTML
  AdminUser Load (0.3ms)  SELECT  "admin_users".* FROM "admin_users"  WHERE "admin_users"."id" = 1  ORDER BY "admin_users"."id" ASC LIMIT 1
   (1.2ms)  SELECT COUNT(*) FROM "show_requests"  WHERE (not_going_to_show = 'f' OR i_want_my_horse_to_compete = 't')
   (0.2ms)  SELECT COUNT(*) FROM "show_requests"
   (0.2ms)  SELECT COUNT(*) FROM "show_requests"  WHERE (not_going_to_show = 't' AND i_want_my_horse_to_compete = 'f')
   (0.3ms)  SELECT COUNT(count_column) FROM (SELECT  1 AS count_column FROM "show_requests"  WHERE (not_going_to_show = 'f' OR i_want_my_horse_to_compete = 't') LIMIT 30 OFFSET 0) subquery_for_count
  CACHE (0.0ms)  SELECT COUNT(count_column) FROM (SELECT  1 AS count_column FROM "show_requests"  WHERE (not_going_to_show = 'f' OR i_want_my_horse_to_compete = 't') LIMIT 30 OFFSET 0) subquery_for_count
  CACHE (0.0ms)  SELECT COUNT(*) FROM "show_requests"  WHERE (not_going_to_show = 'f' OR i_want_my_horse_to_compete = 't')
  CACHE (0.0ms)  SELECT COUNT(count_column) FROM (SELECT  1 AS count_column FROM "show_requests"  WHERE (not_going_to_show = 'f' OR i_want_my_horse_to_compete = 't') LIMIT 30 OFFSET 0) subquery_for_count
  ShowRequest Load (2.0ms)  SELECT  "show_requests".* FROM "show_requests"  WHERE (not_going_to_show = 'f' OR i_want_my_horse_to_compete = 't')  ORDER BY "show_requests"."id" desc LIMIT 30 OFFSET 0
  Show Load (9.7ms)  SELECT "shows".* FROM "shows"  WHERE "shows"."id" IN (2, 1)
  User Load (0.4ms)  SELECT  "users".* FROM "users"  WHERE "users"."id" = $1 LIMIT 1  [["id", 2]]
  User Load (0.2ms)  SELECT  "users".* FROM "users"  WHERE "users"."id" = $1 LIMIT 1  [["id", 1]]
  CACHE (0.0ms)  SELECT  "users".* FROM "users"  WHERE "users"."id" = $1 LIMIT 1  [["id", 1]]
  Show Load (0.2ms)  SELECT "shows".* FROM "shows"
  User Load (0.2ms)  SELECT "users".* FROM "users"

这不起作用。它根本不影响列的顺序。我该如何解决这个问题？

Answer 1

看看这部分日志：

ShowRequest Load (2.0ms)  SELECT  "show_requests".* FROM "show_requests"  WHERE (not_going_to_show = 'f' OR i_want_my_horse_to_compete = 't')  ORDER BY "show_requests"."id" desc LIMIT 30 OFFSET 0
Show Load (9.7ms)  SELECT "shows".* FROM "shows"  WHERE "shows"."id" IN (2, 1)

您可以看到ShowRequests 和Shows 在单独的查询中加载。 sortable 在这里不起作用，因为您不能在没有连接的情况下按另一个表的字段排序一个表。解决方法应该是告诉 ActiveRecord 您需要在查询中引用 shows 表：

controller do
  def scoped_collection
    super.includes(:show).references(:shows)
  end
end

index do
  column :show, sortable: 'shows.created_at'
end

references 仅适用于includes，并在急切加载时强制 Rails 执行连接。