Question

我有以下课程，

class Event < ActiveRecord::Base

  has_many :user_calendars, :dependent => :destroy
  belongs_to :user

end



class User < ActiveRecord::Base
  has_many :events
  has_many :user_calendars


end

class UserCalendar < ActiveRecord::Base
  belongs_to :event
   belongs_to :user
end

我希望能够找到属于最多usercalendars的前n个事件

我创建了以下函数来获取将用户添加到用户日历的用户数。

@count = UserCalendar.where('event_id = ?', event_id).count

我仍然不确定添加顶部的最佳方式是什么。

Answer 1

此查询将提供event_id n次

select *,count(*) as count from user_calendar group by event_id having count(*) = n order by count desc

在Rails中实现

# Replace n with yours
event_ids = UserEvent.find_by_sql("select *,count(*) as count from user_calendar group by event_id having count(*) = n order by count desc").map(&:id) rescue []

Event.where("id in (?)",event_ids)

注意：根据我的理解，您希望UserEvent中的event_ids不会发生。如果我错了就发表评论。

找到最多添加的员工

1 个答案: