mysql - Activerecord 对 sql 的转换不正确

Question

我正在使用 rails 3.2.3、rspec 2.9.0、mysql5.1

原来的请求是

def index
  @votes = current_contest.votes.select('COUNT(*) AS votes_count, submission_id').group('submission_id').order('votes_count DESC')
end

在开发环境中一切正常，但在我的测试中我得到了错误(ActiveRecord 添加额外的别名并重写我的)

ActionView::Template::Error:
   Mysql2::Error: Unknown column 'votes_count' in 'order clause': SELECT COUNT(*) AS count_all, submission_id AS submission_id FROM `votes` INNER JOIN `invitations` ON `votes`.`invitation_id` = `invitations`.`id` WHERE `invitations`.`contest_id` = 1 AND (`invitations`.`status` = 'used') GROUP BY submission_id ORDER BY votes_count DESC

我可以通过这样的简单查询捕获此错误

def index    
  @votes = Vote.select('COUNT(*) AS votes_count, submission_id')
end

日志输出为

SELECT COUNT(*) FROM `votes`

但是!!!如果我这样做

def index    
  @votes = Vote.select('COUNT(*) AS votes_count, submission_id')
  @votes.inspect # or something else calling @votes
end

我在控制台日志中得到了正确的 sql 查询

SELECT COUNT(*) AS votes_count, submission_id FROM `votes`

Answer 1

我想，你调用类似的东西

if @votes.any?

在你看来。

方法 any? 将对表中的记录进行计数。例如，Vote.any? 会产生如下内容:

SELECT COUNT(*) AS count_all FROM `votes`;

在您的情况下，您的 COUNT(*) AS votes_count 将替换为 COUNT(*) AS count_all，但别名 votes_count 将是留在订单条款中。

SELECT COUNT(*) AS count_all, submission_id AS submission_id FROM `votes` 
  INNER JOIN `invitations` ON `votes`.`invitation_id` = `invitations`.`id` 
WHERE `invitations`.`contest_id` = 1 AND (`invitations`.`status` = 'used') 
GROUP BY submission_id 
ORDER BY votes_count DESC