Convert Time from one time zone to another in Rails

Question

My created_at timestamps are stored in UTC:

>> Annotation.last.created_at
=> Sat, 29 Aug 2009 23:30:09 UTC +00:00

How

Answer 1

Although this is an old question, it's worth mentioning something. In a previous reply it's suggested to use a before_filter to set the timezone temporally.

You should never, ever do that because Time.zone stores the information in the thread, and it will probably leak to the next request handled by that thread.

Instead you should use an around_filter to make sure that the Time.zone is reset after the request is complete. Something like:

around_filter :set_time_zone

private

def set_time_zone
  old_time_zone = Time.zone
  Time.zone = current_user.time_zone if logged_in?
  yield
ensure
  Time.zone = old_time_zone
end

Read more about this here

Answer 2

Use the in_time_zone method of the DateTime class

Loading development environment (Rails 2.3.2)
>> now = DateTime.now.utc
=> Sun, 06 Sep 2009 22:27:45 +0000
>> now.in_time_zone('Eastern Time (US & Canada)')
=> Sun, 06 Sep 2009 18:27:45 EDT -04:00
>> quit

So for your particular example

Annotation.last.created_at.in_time_zone('Eastern Time (US & Canada)')

Answer 3

If you configure your /config/application.rb

config.time_zone = 'Eastern Time (US & Canada)'

Time.now.in_time_zone

DateTime.now.in_time_zone

Answer 4

If you add this to your /config/application.rb

config.time_zone = 'Eastern Time (US & Canada)'

Then you can cell

Annotation.last.created_at.in_time_zone

to get the time in the specified time zone.

Answer 5

Set your timezone to Eastern Time.

You can set your default timezone in config/environment.rb

config.time_zone = "Eastern Time (US & Canada)"

Now all records you pull out will be in that time zone. If you need different time zones, say based on a user timezone you can change it with a before_filter in your controller.

class ApplicationController < ActionController::Base

  before_filter :set_timezone

  def set_timezone
    Time.zone = current_user.time_zone
  end
end

Just make sure you are storing all your times in the database as UTC and everything will be sweet.