I’v found out that the view still communicates with the database (17 Queries):

不需要这17个额外查询.因为我已经从控制台测试了控制器查询,并且它成功地收集了部分_dropdown(在5个查询中)所需的所有数据,而没有任何进一步的数据库通信.

这是我的控制器中的query,它是为了避免N 1问题. (包括视图中调用的所有变量)

这是下拉代码：

- @messages.each do |message|
    %li.conversation-container
        %a{href: conversation_path(message.conversation_id)}
            - if message.sender != current_user 
                .notification-avatar{style: "background: url(#{message.sender.avatar_url}); background-size: contain; background-repeat: no-repeat; background-position: 50% 50%;"}
            - else
                - other_participant = message.conversation.conversation_participants.select{|p| p.user_id != current_user.id }.first.user 
                .notification-avatar{style: "background: url(#{other_participant.avatar_url}); background-size: contain; background-repeat: no-repeat; background-position: 50% 50%;"}
            %p
                %strong
                    - if message.sender != current_user 
                        = message.sender.name
                    - else
                        = other_participant.name
                %br
                - if message.sender == current_user
                    %i.fa.fa-mail-reply-all
                = truncate(message.body,length: 25)

                .time
                    = time_ago_in_words(message.created_at)
                    ago
- if @messages.count == 0
    %li
        .empty-state-text-white
            No messages

控制台输出：

2.0.0-p353 :006 > ms = Message.dropdown_for(3).all
  Message Load (1.2ms)  SELECT "messages".* FROM "messages" LEFT JOIN messages AS m ON messages.id != m.id 
 AND m.conversation_id = messages.conversation_id 
 AND messages.created_at < m.created_at INNER JOIN conversation_participants AS cp ON cp.conversation_id = messages.conversation_id AND cp.user_id = 3 WHERE (m.id IS NULL) ORDER BY cp.seen,cp.updated_at DESC LIMIT 5
  User Load (0.7ms)  SELECT "users".* FROM "users" WHERE "users"."id" IN (6,4,5)
  Conversation Load (0.4ms)  SELECT "conversations".* FROM "conversations" WHERE "conversations"."id" IN (4,2,3)
  ConversationParticipant Load (0.2ms)  SELECT "conversation_participants".* FROM "conversation_participants" WHERE "conversation_participants"."conversation_id" IN (4,3)
  User Load (0.6ms)  SELECT "users".* FROM "users" WHERE "users"."id" IN (6,3,5)
 => [#<Message id: 8,body: "saSasa",sender_id: 6,conversation_id: 4,sent: true,attachment_id: nil,attachment_type: nil,created_at: "2014-11-17 16:05:40",updated_at: "2014-11-17 16:05:40">,#<Message id: 2,body: "asdnas dagsdashjdg jahs d",sender_id: 4,conversation_id: 2,created_at: "2014-11-17 11:32:36",updated_at: "2014-11-17 11:32:36">,#<Message id: 6,body: "SADASD A DSA ",sender_id: 5,conversation_id: 3,created_at: "2014-11-17 13:43:34",updated_at: "2014-11-17 13:43:34">] 

2.0.0-p353 :007 > ms.first.conversation.conversation_participants.select{|cp| cp.user_id != 3}.first.user
 => #<User id: 6,first_name: "Ddsfsd",middle_name: nil,last_name: "Fsdfsd",photo: nil,email: "1@k.com",encrypted_password: "$2a$10$5sGIb2DbQ1ctMrTzD3AJ0uV18hhiC5Ei1wcfE7MSAvRU...",reset_password_token: nil,reset_password_sent_at: nil,remember_created_at: nil,sign_in_count: 1,current_sign_in_at: "2014-11-17 15:27:06",last_sign_in_at: "2014-11-17 15:27:06",current_sign_in_ip: "127.0.0.1",last_sign_in_ip: "127.0.0.1",confirmation_token: nil,confirmed_at: "2014-11-17 15:27:48",confirmation_sent_at: "2014-11-17 15:27:05",unconfirmed_email: nil,Failed_attempts: 0,unlock_token: nil,locked_at: nil,authentication_token: nil,created_at: "2014-11-17 15:27:05",updated_at: "2014-11-17 15:27:48",slug: "ddsfsd_fsdfsd"> 

2.0.0-p353 :008 > ms.count
 => 3

如何在没有目的的情况下阻止这些查询运行？