ar_after_timestamps

A little gem that gives you a way to add a callback to the ActiveRecord callback chain that will be executed right after the record's timestamp columns are set, but before the record is actually saved to the database. This is useful if you want to do something with the timestamps, such as defaulting another time column to created_at, or rolling back a timestamp by a certain amount.

Let's say you have a migration like this:

class AddFoo < ActiveRecord::Migration
  def self.up
    create_table :foo {|t| t.timestamps }
  end
  def self.down
    drop_table :foo
  end
end

And a model like this:

class Foo < ActiveRecord::Base
  after_timestamps_on_create :roll_back_created_at_by_two_hours
  after_timestamps_on_update :roll_back_updated_at_by_two_hours

private
  def roll_back_created_at_by_two_hours
    self.created_at -= 2.hours
  end

  def roll_back_updated_at_by_two_hours
    self.updated_at -= 2.hours
  end
end

Now if you say

Foo.create!

created_at and updated_at will be set, but 2 hours will be subtracted from them before they're put into the database.

1. Run gem install ar_after_timestamps (probably as root)
2. Add config.gem 'ar_after_timestamps' to environment.rb
3. Optionally run rake gems:build

If you find any bugs with this plugin, feel free to:

• file a bug report in the Issues area on Github
• fork the project on Github and send me a pull request
• email me (firstname dot lastname at gmail dot com)

(c) 2008-2010 Elliot Winkler. See LICENSE for details.