由周/月/等及放大器分组; ActiveRecord的？ [英] Grouping by week/month/etc & ActiveRecord?

问题描述

我正在做一些静态计算我的产品。用户已经执行了一些操作，让我们说张贴。我希望能够向他们展示他们有多少意见，每周发布在过去的一个月，或每月在过去的一年。

I'm doing some statics calculation in my product. A user has performed a number of operations, let's say posted comments. I want to be able to show them how many comments they've posted per week for the past month, or per month for the past year.

有没有办法通过ActiveRecord组这样？是我最好最好只是手工做？ - 遍历记录求和根据我自己的标准

Is there any way with activerecord to group this way? Is my best best to simply do this manually - to iterate over the records summing based on my own criteria?

class User < ActiveRecord::Base
  has_many :comments
end

class Comments < ActiveRecord::Base
  belongs_to :user
end

@user.comments(:all).map {|c| ...do my calculations here...}

或者是有一些更好的办法？

or is there some better way?

感谢！ 奥伦

推荐答案

在这种情况下，对我来说最好的解决办法是要么做直SQL，或者使用ActiveRecord的GROUP_BY功能：

In this case, the best solution for me was to either do it in straight SQL, or to use the activerecord group_by function:

@user.all.group_by{ |u| u.created_at.beginning_of_month }

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