How to get Rails to interpret a time as being in a specific time zone?

Question

In Ruby 1.8.7, how to set the time zone of a time?

In the following examples, my system time zone is PST (-8:00 hours from UTC)

Given a time (21 Feb 2011

Answer 1

So I think this will (almost) accomplish what you want:

require 'time'
t = "21 Feb 2011, 20:45"
Time.parse(t)           # => Mon Feb 21 20:45:00 -0700 2011
t += " -05:00"          # this is the trick
Time.parse(t)           # => Mon Feb 21 18:45:00 -0700 2011

It still returns the time based on your system time zone, but the actual time is the correct time that you are seeking.

By the way, this is tested on 1.8.7-p334.

Answer 2

In ruby 1.8.7 it doesn't appear to be very easy to do what are asking for according to the documentation:

http://www.ruby-doc.org/core-1.8.7/classes/Time.html

However in 1.9 it looks a lot easier by passing the timezone offset to the localtime() method on a Time object:

http://www.ruby-doc.org/core/classes/Time.html#M000346

UPDATE

The offset for Time.zone is easy since its an object on its own: (This is in a Rails console)

ruby-1.8.7-p248 :001 > Time.zone
 => #<ActiveSupport::TimeZone:0x103150190 @current_period=nil, @name="Central Time (US & Canada)", @tzinfo=#<TZInfo::TimezoneProxy: America/Chicago>, @utc_offset=nil> 
ruby-1.8.7-p248 :002 > Time.zone.utc_offset
 => -21600 
ruby-1.8.7-p248 :003 > Time.zone.formatted_offset
 => "-06:00"