script/console
>> t = Time.at(1158609371)
=> Mon Sep 18 20:56:11 +0100 2006
>> t.zone
=> "BST"
>> s = Shop.find(:first)
>> s.creation_tsz = t.utc
=> Mon Sep 18 19:56:11 UTC 2006
>> s.creation_tsz.zone
=> "UTC"
>> s.save
>> s = Shop.find(:first)
>> s.creation_tsz
=> Sat Jan 01 19:56:11 UTC 2000
How come it changed from Sep 18 2006 to Jan 01 2000? Timezone is setup to use "UTC" in environment.rb. And just so you are aware I have tried numerous variations of line s.creation_tsz = t.utc . All with failure.
Is it possible that in the database, s.creation_tsz stores only a time, but not a date part, for example a MySQL TIME type, as opposed to the TIMESTAMP or DATETIME type.
Related
I extended the Time class in my Rails projects so I can easily get the time in NYC:
/lib/extensions.rb .
class Time
# Get NYC time:
def nyc
self.in_time_zone('Eastern Time (US & Canada)')
end
end
Testing it out, looks good:
time_a = Time.now.utc.nyc
=> Sun, 21 Apr 2019 18:42:12 EDT -04:00
The problem is when I pull timestamps from the DB:
time_b = object.created_at.in_time_zone('Eastern Time (US & Canada)')
=> Sun, 21 Apr 2019 17:22:04 EDT -04:00
time_c = object.created_at.nyc
=> Sun, 21 Apr 2019 17:22:04 UTC +00:00
Super confused. Converting the timestamp to EDT works when I use in_time_zone in the console, but not when I use the extension? Even though my extension method works on Time objects I create in console? What's happening here?
(Note: Time instances in Rails are in fact instances of ActiveSupport::TimeWithZone. "TimeWithZone instances implement the same API as Ruby Time instances, so that Time and TimeWithZone instances are interchangeable." - ActiveSupportTimeWithZone)
you would need to patch ActiveSupport::TimeWithZone instead of Time, e.g.
class ActiveSupport::TimeWithZone
def nyc
in_time_zone('Eastern Time (US & Canada)')
end
end
Time.zone.now.nyc # => Mon, 22 Apr 2019 06:44:41 EDT -04:00
User.last.created_at.nyc # => Sun, 21 Apr 2019 13:34:45 EDT -04:00
https://api.rubyonrails.org/classes/ActiveSupport/TimeWithZone.html
(edit: I previously said "DateTime" instead of "ActiveSupport::TimeWithZone")
In rails console if I run the following commands I get:
>> Time.zone.name
=> "UTC"
>> Time.now.getlocal
=> 2015-08-06 16:34:57 -0400
I'm in NYC and the utc offset is -4 hours so the getlocal seems to get the system time zone rather than the environment time zone. This becomes an issue when using the String to_time method:
>> s = "2015-08-06 16:34:57"
=> "2015-08-06 16:34:57"
>> s.to_time(:utc)
=> 2015-08-06 16:34:57 UTC
>> s.to_time(:local)
=> 2015-08-06 16:34:57 -0400
>> s.to_time
=> 2015-08-06 16:34:57 -0400
Any ideas why? Can I force it to look at the environment time zone rather than the system time zone?
My main motivation is that my tests are run locally (so system time is in NYC), but my app is hosted on heroku which has UTC server time, so this caused an issue where a bug slipped through my tests and into production =/
You can do the following:
"2015-08-06 16:23:25".to_time.in_time_zone
The default behavior of to_time is to use :local according to the API doc (either :local or :utc are valid). For whatever reason, using in_time_zone appears to respect your configured timezone.
To expand on your above posted examples (from my machine):
» Time.zone.name
=> "UTC"
» Time.now
=> "2015-08-06T13:49:05.195-07:00"
» Time.zone.now
=> Thu, 06 Aug 2015 20:49:17 UTC +00:00
» time_string = "2015-08-06 16:34:57"
=> "2015-08-06 16:34:57"
» time_string.to_time
=> "2015-08-06T16:34:57.000-07:00"
» time_string.to_time.in_time_zone
=> Thu, 06 Aug 2015 23:34:57 UTC +00:00
EDIT: Based on the comment below, you can also do the following to not have any time shift added:
» DateTime.parse(time_string)
=> Thu, 06 Aug 2015 16:34:57 +0000
This will use the configured timezone (UTC in my case)
Here goes :
Time.zone.now => "Eastern Time (US & Canada)"
Time.zone.now => Wed, 15 Aug 2012 06:05:37 EDT -04:00
Time.zone.now + 39.years => Tue, 15 Aug 2051 06:06:03 EST -05:00
And so you have it, the end of our fabled Eastern Daylight Time has been prophesied by Ruby on Rails to end in the year 2051.
Also works for any other TimeZone changing area.
Time.zone
=> "Pacific Time (US & Canada)"
1.9.2p180 :003 > Time.zone.now
=> Wed, 15 Aug 2012 03:08:57 PDT -07:00
1.9.2p180 :004 > Time.zone.now + 39.years
=> Tue, 15 Aug 2051 03:08:57 PST -08:00
This exists in Rails 3.0 and in Rails 3.2.6
Yes, it looks like a bug. It's not Rails, however, it's the Ruby Time class. It has problems with times after 2038.
For example, with Ruby 1.8.7:
> Time.local(2037,8,16,9,30,15)
=> Sun Aug 16 09:30:15 -0400 2037
>
> Time.local(2038,8,16,9,30,15)
=> Mon Aug 16 09:30:15 -0500 2038
JRuby 1.6.7.2 - for instance - does not have this problem:
> Time.local(2038,8,16,9,30,15)
=> Mon Aug 16 09:30:15 -0400 2038
Note that, on MRI Ruby on 64-bit systems, the ActiveSupport time extension which supports the addition of durations ultimately calls Time.local or Time.utc via this method in active_support/core_ext/time/calculations.rb:
# Returns a new Time if requested year can be accommodated by Ruby's Time class
# (i.e., if year is within either 1970..2038 or 1902..2038, depending on system architecture);
# otherwise returns a DateTime
def time_with_datetime_fallback(utc_or_local, year, month=1, day=1, hour=0, min=0, sec=0, usec=0)
::Time.send(utc_or_local, year, month, day, hour, min, sec, usec)
rescue
offset = utc_or_local.to_sym == :local ? ::DateTime.local_offset : 0
::DateTime.civil(year, month, day, hour, min, sec, offset)
end
I guess the issue is that for years >= 2038, they were expecting an overflow exception and for DateTime to be used instead. On 64-bit systems, this doesn't happen.
UPDATE: This analysis is incorrect for Ruby 1.9.2+. Time.local works as expected, but the original problem still occurs.
I have a very strange issue with Daylight Savings Time (DST) in my app. For some reason, whenever I receive a time from the table, it doesn't adjust itself for DST. For example, if I create a new Time in the console, in the appropriate time zone, write it to the database, and then try to retrieve it from the database, it comes back as one hour earlier.
Here's an example:
Here, we can see that using the console, creating a new Time at 15:00 EST is equal to 19:00 UTC (since adjusted for DST, which makes it -0400 instead of the usual -0500):
ruby-1.8.6-p114 > Time.zone
=> #<ActiveSupport::TimeZone:0x12b1b68 #name="UTC", #tzinfo=nil, #utc_offset=0>
ruby-1.8.6-p114 > Time.zone = "Eastern Time (US & Canada)"
=> "Eastern Time (US & Canada)"
ruby-1.8.6-p114 > Time.zone.parse("15:00")
=> Thu, 09 Sep 2010 15:00:00 EDT -04:00
ruby-1.8.6-p114 > Time.zone.parse("15:00").utc
=> Thu Sep 09 19:00:00 UTC 2010
ruby-1.8.6-p114 > Time.zone.parse("15:00").dst?
=> true
Now, I try to write that same time to the database, and retrieve it back:
ruby-1.8.6-p114 > b = Book.new
=> #<Book id: nil, return_time: nil, created_at: nil, updated_at: nil>
ruby-1.8.6-p114 > b.return_time = Time.zone.parse("15:00")
=> Thu, 09 Sep 2010 15:00:00 EDT -04:00
ruby-1.8.6-p114 > b.save
=> true
ruby-1.8.6-p114 > result = Book.find(:last).return_time
=> Sat Jan 01 19:00:00 UTC 2000
ruby-1.8.6-p114 > result.zone
=> "UTC"
ruby-1.8.6-p114 > result.in_time_zone
=> Sat, 01 Jan 2000 14:00:00 EST -05:00
ruby-1.8.6-p114 > result.dst?
=> false
My environment.rb has this:
config.time_zone = 'UTC'
And application_controller.rb has this:
before_filter :set_user_time_zone
def set_user_time_zone
if current_user
Time.zone = current_user.time_zone
else
Rails.logger.error '[Time.zone.now.to_s][ERROR]: Missing current_user from in set_user_time_zone!'
end
end
Any ideas as to what could be happening here and how to fix it? I've been at this for days now, so really, any help would be greatly appreciated!
Thank you very much.
It looks like you're only saving the time portion; note how the date part goes from Thu, 09 Sep 2010 to Sat, 01 Jan 2000. Since the DST calculation depends on the date, this is probably where you're losing the information. (January 1st is not in DST, so assuming that date, the DST calculation is correct). You probably need to save a DATETIME in the database, not just TIME.
I'm not sure what version of Rails you're using, but I had the same problem in 2.1.2. It seems the time zone library included just doesn't work half the year, but the developers didn't think it was worth switching; hopefully they've rethought that decision by now.
In any case, we ended up using the tzinfo_timezone plugin, which computes UTC offsets correctly during daylight savings time.
Rails' ActiveSupport module extends the builtin ruby Time class with a number of methods.
Notably, there is the to_formatted_s method, which lets you write Time.now.to_formatted_s(:db) to get a string in Database format, rather than having to write ugly strftime format-strings everywhere.
My question is, is there a way to go backwards?
Something like Time.parse_formatted_s(:db) which would parse a string in Database format, returning a new Time object. This seems like something that rails should be providing, but if it is, I can't find it.
Am I just not able to find it, or do I need to write it myself?
Thanks
It looks like ActiveSupport does provide the parsing methods you are looking for (and I was looking for too), after all! — at least if the string you are trying to parse is a standard, ISO-8601-formatted (:db format) date.
If the date you're trying to parse is already in your local time zone, it's really easy!
> Time.zone.parse('2009-09-24 08:28:43')
=> Thu, 24 Sep 2009 08:28:43 PDT -07:00
> Time.zone.parse('2009-09-24 08:28:43').class
=> ActiveSupport::TimeWithZone
and that time-zone-aware time can then easily be converted to UTC
> Time.zone.parse('2009-09-24 08:28:43').utc
=> 2009-09-24 15:28:43 UTC
or to other time zones:
> ActiveSupport::TimeZone.us_zones.map(&:name)
=> ["Hawaii", "Alaska", "Pacific Time (US & Canada)", "Arizona", "Mountain Time (US & Canada)", "Central Time (US & Canada)", "Eastern Time (US & Canada)", "Indiana (East)"]
> Time.zone.parse('2009-09-24 08:28:43').utc.in_time_zone('Eastern Time (US & Canada)')
=> Thu, 24 Sep 2009 11:28:43 EDT -04:00
If the date string you're trying to parse is in UTC, on the other hand, it doesn't look like there's any method to parse it directly into a TimeWithZone, but I was able to work around that be first using DateTime.strptime...
If the date you're trying to parse is in UTC and you want it to stay as UTC, you can use:
> DateTime.strptime('2009-09-24 08:28:43', '%Y-%m-%d %H:%M:%S').to_time
=> 2009-09-24 08:28:43 UTC
If the date you're trying to parse is in UTC and you want it converted to your default time zone, you can use:
> DateTime.strptime('2009-09-24 08:28:43', '%Y-%m-%d %H:%M:%S').to_time.in_time_zone
=> Thu, 24 Sep 2009 01:28:43 PDT -07:00
It looks like it can even parse other formats, such as the strange format that Time#to_s produces:
irb -> Time.zone.parse('Wed, 23 Sep 2009 02:18:08').to_s(:db)
=> "2009-09-23 09:18:08"
irb -> Time.zone.parse('Wed, 23 Sep 2009 02:18:08 EDT').to_s(:db)
=> "2009-09-23 06:18:08"
I'm quite impressed.
Here are some more examples from [http://api.rubyonrails.org/classes/ActiveSupport/TimeWithZone.html][1]:
Time.zone = 'Eastern Time (US & Canada)' # => 'Eastern Time (US & Canada)'
Time.zone.local(2007, 2, 10, 15, 30, 45) # => Sat, 10 Feb 2007 15:30:45 EST -05:00
Time.zone.parse('2007-02-10 15:30:45') # => Sat, 10 Feb 2007 15:30:45 EST -05:00
Time.zone.at(1170361845) # => Sat, 10 Feb 2007 15:30:45 EST -05:00
Time.zone.now # => Sun, 18 May 2008 13:07:55 EDT -04:00
Time.utc(2007, 2, 10, 20, 30, 45).in_time_zone # => Sat, 10 Feb 2007 15:30:45 EST -05:00
More documentation links for reference:
http://api.rubyonrails.org/classes/ActiveSupport/TimeWithZone.html
http://api.rubyonrails.org/classes/ActiveSupport/TimeZone.html
ActiveSupport::TimeZone.new('UTC').parse('2009-09-23 09:18:08')
=> Wed, 23 Sep 2009 09:18:08 UTC +00:00
Rails 5 finally provides strptime!
value = '1999-12-31 14:00:00'
format = '%Y-%m-%d %H:%M:%S'
Time.zone.strptime(value, format)
# => Fri, 31 Dec 1999 14:00:00 HST -10:00
ActiveSupport::TimeZone.all.sample.strptime(value, format)
# => Fri, 31 Dec 1999 14:00:00 GST +04:00
I just ran into this as well and none of the above answers were satisfactory to me. Ideally one could use ActiveSupport::TimeZone just like Time and call .strptime on it with any arbitrary format and get back the correct TimeZone object. ActiveSupport::TimeZone.strptime doesn't exist so I created this monkeypatch:
class ActiveSupport::TimeZone
def strptime(str, fmt, now = self.now)
date_parts = Date._strptime(str, fmt)
return if date_parts.blank?
time = Time.strptime(str, fmt, now) rescue DateTime.strptime(str, fmt, now)
if date_parts[:offset].nil?
ActiveSupport::TimeWithZone.new(nil, self, time)
else
time.in_time_zone(self)
end
end
end
>> "2009-09-24".to_date
=> Thu, 24 Sep 2009
>> "9/24/2009".to_date
=> Thu, 24 Sep 2009
Works great unless your date is in some weird format.