How to Get Ruby to Parse Time as If It Were in a Different Time Zone

How do I get Ruby to parse time as if it were in a different time zone?

You could just append the UTC timezone name to the string before parsing it:

require 'time'
s = "11/23/10 23:29:57"
Time.parse(s) # => Tue Nov 23 23:29:57 -0800 2010
s += " UTC"
Time.parse(s) # => Tue Nov 23 23:29:57 UTC 2010

Rails: How to parse date-time string into a specific time zone

%Z is the correct way to specify a Time zone name. Have you tried the following ?

date_and_time = '%m-%d-%Y %H:%M:%S %Z'
DateTime.strptime("04-15-2010 10:00:00 Central Time (US & Canada)",date_and_time)

How can I use Ruby to parse a time as though it is in a time zone I specify, with zone in the format America/Los_Angeles?

Here's what I came up with using the tzinfo gem as suggested, though it seems rather complicated and unintuitive to me. As an end result I get the time parsed as though it were in the time zone I wanted, though represented by a Time object in UTC. I can also display it in the time zone I want using tzinfo's strftime:

jruby-1.6.1 :003 > time = '2010-05-01 01:00:00'
 => "2010-05-01 01:00:00" 
jruby-1.6.1 :004 > tz = TZInfo::Timezone.get('America/New_York')
 => #<TZInfo::DataTimezone: America/New_York> 
jruby-1.6.1 :005 > time += ' UTC'
 => "2010-05-01 01:00:00 UTC" 
jruby-1.6.1 :006 > time = Time.parse(time)
 => Sat May 01 01:00:00 UTC 2010 
jruby-1.6.1 :007 > time = tz.local_to_utc(time)
 => Sat May 01 05:00:00 UTC 2010 
jruby-1.6.1 :010 > tz.strftime('%Y-%m-%d %H:%M:%S %Z', time)
 => "2010-05-01 01:00:00 EDT"

I believe this will suit my needs, but I wonder if I can get the Time to actually be in the timezone above (instead of just UTC).

Rails - A better way to parse the time with a timezone?

Were you looking for a specific timezone of the current local one?

# Current zone
1.9.3p194> Time.zone.parse('2012-12-25T00:00:00+09:00')
=> Mon, 24 Dec 2012 15:00:00 UTC +00:00

Console was set at UTC for above but will work for whatever you have configured

# Specific timezone 
1.9.3p194> Time.find_zone('Wellington').parse('2012-12-25T00:00:00+09:00')
=> Tue, 25 Dec 2012 04:00:00 NZDT +13:00

I notice you're trying to pass +9 so as an example

1.9.3p194> Time.zone = 'Tokyo'
=> "Tokyo" 
1.9.3p194> Time.zone.parse('2012-12-25T00:00:00+09:00')
=> Tue, 25 Dec 2012 00:00:00 JST +09:00

Gives you the right result.

Which should I always parse date times with? DateTime, Time, Time.zone?

Go with Time.zone.parse if you just want to write into ActiveRecord.

DateTime should be avoided. If you're handling dates, you should use Date.parse instead.

Beyond that, it depends on whether the input comes with timezone information, what the current timezone is set to, and whether you want timezones in your data.

Time.zone.parse will return an ActiveSupport::TimeWithZone, defaulting to UTC.

> Time.zone.parse("12:30")
=> Thu, 10 May 2012 12:30:00 UTC +00:00

Time.parse will return a Time, with a zone if it's specified in the input, or the local TZ.

> Time.parse("12:30")
=> 2012-05-09 12:30:00 -0700

For a more detailed explanation of Ruby time comparisons and precision, read this blog post:

http://blog.solanolabs.com/rails-time-comparisons-devil-details-etc/