Set current Time.zone in Rails?

Question

Javascript on my page saves client UTC offset to the cookie. How do I use this cookie to create a TimeZone and assign it to Time.zone ?

I need something like:

before_filter :set_time_zone

def set_time_zone
  Time.zone = ActiveSupport::TimeZone.new('my timezone', cookies[:timezone])
end

except that the right part of this expression does not work and I'm not sure if I'm going the right way here. Can't get it.

Answer 1

Here's the working googled answer:

min = cookies[:timezone].to_i
Time.zone = ActiveSupport::TimeZone[-min.minutes]

Just to make it clear, the javascript part:

if(!($.cookie('timezone'))) {
  current_time = new Date();
  $.cookie('timezone', current_time.getTimezoneOffset(), { path: '/', expires: 10 } );
} 

Answer 2

@snitko - you're answer worked great for me for a long time. However, as @Giovanni pointed out, it doesn't account for daylight savings time in some scenarios since it pulls the first timezone available given the minute offset. I've found a simple working answer that accounts for DST.

Head here - http://site.pageloom.com/automatic-timezone-detection-with-javascript, it's a javascript timezone detector. You simply copy the javascript code linked from the website (or right here) into your one of your app's javascript files (application.js works fine). It allows you to retrieve the timezone through an object named jstz.

Then, in application.html.erb I have

<script type="text/javascript">

  var timezone = jstz.determine();
  document.cookie = 'time_zone='+timezone.name()+';';

</script>

And in application_controller.rb, I have

before_filter :set_timezone 

private
def set_timezone
  Time.zone = cookies["time_zone"]
end

And that's all you need! Time zone is set properly for your Rails app.

EDIT: It's possible you need to place the javascript cookie setting code after your <\body> tag in application.html.erb due to the different way and order javascript files are loaded up.