I ran into a Rails 3.0.1 timezone issue today that I didn’t see discussed many other places.

Basically, I just want to have a page in my app that shows the time in different time zones. That seems simple and something tailor suited for timezone support.

I started with this:

>> Time.now.in_time_zone('EST')
=> Tue, 23 Nov 2010 11:09:42 EST -05:00

Okay, so far so good. Next:

>> Time.now.in_time_zone('PST')
NoMethodError: undefined method `period_for_utc' for nil:NilClass
[...]

>> Time.now.in_time_zone('CST')
NoMethodError: undefined method `period_for_utc' for nil:NilClass
[...]

Wait, that’s odd… why doesn’t that work? After searching, I found you could use some city names like so:

>> Time.now.in_time_zone('Tokyo')
=> Wed, 24 Nov 2010 01:04:54 JST +09:00

But of course JST won’t work:

>> Time.now.in_time_zone('JST')
NoMethodError: undefined method `period_for_utc' for nil:NilClass
[...]

And neither will major American cities:

>> Time.now.in_time_zone('New York')
NoMethodError: undefined method `period_for_utc' for nil:NilClass
[...]

>> Time.now.in_time_zone('Chicago')
NoMethodError: undefined method `period_for_utc' for nil:NilClass
[...]

Nothing too relevant came up when I googled the above errors and phrases (part of why I’m posting this), but then I came across the rake time:zones:us and rake time:zones:all Rake tasks. They list valid timezones for you.

The thing that gets me is that 'EST' and 'Tokyo' work as expected, but 'PST' and 'New York' don’t. These are what I ended up with:

>> Time.now.in_time_zone('Eastern Time (US & Canada)')
=> Tue, 23 Nov 2010 11:08:12 EST -05:00
>> Time.now.in_time_zone('Central Time (US & Canada)')
=> Tue, 23 Nov 2010 10:06:08 CST -06:00
>> Time.now.in_time_zone('Pacific Time (US & Canada)')
=> Tue, 23 Nov 2010 08:06:23 PST -08:00

Ironically, it lists EST, CST, and PST in the results. It’s still confusing to me why the longhand version is the preferred notation here (sometimes), but at least you’re given the tools to look it up.

Like always, let me know if this post helps you through an error. We’re all in this together.

Update: The good people over at Airbnb found this post helpful when upgrading from Rails 2.3 to 3.0. I’m glad it helped you out!