按天对Mongoid对象进行分组 [英] Grouping Mongoid Objects by Day

问题描述

在控制台中进行了大量的操作之后，我想出了一种方法，可以将类似于activerecord的对象(Mongoid)按发生的日期进行分组.我不确定这是否是实现此目标的最佳方法，但它确实有效.有没有人有更好的建议，或者这是一个好方法吗?

After much playing around in the console, I came up with this method to group activerecord-like (Mongoid) objects by the day on which they occured. I'm not sure this is the best way to accomplish this, but it works. Does anyone have a better suggestion, or is this a good way to do it?

#events is an array of activerecord-like objects that include a time attribute
events.map{ |event|
  # convert events array into an array of hashes with the day of the month and the event
  { :number => event.time.day, :event => event }
}.reduce({}){ |memo,day|
  # convert this into a hash with arrays of events keyed by their day or occurrance
  ( memo[day[:number]] ||= [] ) << day[:event]
  memo
}

=>  {
      29 => [e1, e2],
      28 => [e3, e4, e5],
      27 => [e6, e7],
      ...
    }

谢谢！

推荐答案

经过进一步的思考和Forrst的一些帮助，我想到了:

After more thought and some help from Forrst, I came up with this:

events.inject({}) do |memo,event|
  ( memo[event.time.day] ||= [] ) << event
  memo
end

显然，Rails的monkeypatches可通过这样的#group_by方法枚举:

Apparently Rails monkeypatches Enumerable with a #group_by method that works like this:

events.group_by { |event| event.time.day }

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