Ruby return only date older than 2 days ago - undefined method `days' for 2:Integer

Question

I array below I want to get only days which are older than 2.days.ago

data = ["2020-02-21T07:52:14.114+0100",
 "2020-02-19T13:20:50.539+0100",
 "2020-02-11T12:36:16.565+0100",
 "2020-02-17T20:06:53.312+0100",
 "2020-02-04T09:42:30.754+0100",
 "2020-01-29T13:46:16.033+0100",
 "2020-02-18T11:15:12.894+0100"]

I'm trying to do this with code below:

data.select { |data| data if DateTime.parse(data) > 2.days.ago }

But I'm getting an error:

NoMethodError: undefined method `days' for 2:Integer

Answer 1

As others already pointed out in the comments, n.days.ago is not part of plain Ruby but is introduced with Ruby on Rails (see docs about days and ago ).

The equivalent to n.day.ago in plain Ruby might be something like this:

 Time.now - n * 24 * 60 * 60

That means when you want to select dates that are older than 2 days then you can write your example like this:

 two_days_ago = Time.now - 2 * 24 * 60 * 60
 data.select { |data| Time.parse(data) < two_days_ago }

Please note there is no need for the date if part in the select block.