How to get previous day on UTC time using ruby?
Currently I'm using Time.now.utc.iso8601 to get UTC time format in ruby, I need previous day in same UTC format. Can someone help me with sample code to get previous day?
> Time.now.utc
=> 2015-03-22 19:00:46 UTC
> Time.now.utc - 86400
=> 2015-03-21 19:00:51 UTC
> (Time.now.utc - 86400).iso8601
=> "2015-03-21T19:00:59Z"
Related
This question already has answers here:
Rails: How to parse date-time string into a specific time zone
(7 answers)
Closed 6 years ago.
> input = "12/31/2015 23:59"
> format = "%m/%d/%Y %H:%M"
> Time.zone = "US/Eastern"
> Time.zone.utc_offset
=> -18000
> Time.strptime(input, format)
=> 2015-12-31 23:59:00 +0100
> DateTime.strptime(input, format)
=> Thu, 31 Dec 2015 23:59:00 +0000
Whereas I want to get 2015-12-31 23:59:00 -0500
As you can see both versions of strptime ignore configured time zone (one uses UTC and one uses system/machine time zone).
How to parse given input in custom format in Time.zone?
One solution would be to convert parsed time into ISO string, strip incorrect time zone information and parse again, this time using Time.zone.parse which uses Time.zone:
> parsed = Time.strptime(input, "%m/%d/%Y %H:%M")
> Time.zone.parse(parsed.to_s.gsub(/\+\d\d:?\d\d/, ""))
=> 2015-12-31 23:59:00 -0500
One solution would be to convert parsed time into ISO string, strip incorrect time zone information and parse again, this time using Time.zone.parse which uses Time.zone:
> parsed = Time.strptime(input, "%m/%d/%Y %H:%M")
> Time.zone.parse(parsed.to_s.gsub(/\+\d\d:?\d\d/, ""))
=> 2015-12-31 23:59:00 -0500
It's also possible to append time zone to input (and format):
> DateTime.strptime(input + Time.zone.name, format + " %Z")
=> Thu, 31 Dec 2015 23:59:00 -0500
Both solutions seem like a hackish and I was hoping something more elegant.
I am capturing the current time like so:
Time.now
My server runs on UTC. How can I convert the time to EST without using any Rails libraries? I am guessing some sort of offset but not sure how it works per say.
In plain Ruby you may use Time.zone_offset method:
require 'time'
t = Time.now # 2014-07-30 18:30:00 UTC
t + Time.zone_offset('EST') # 2014-07-30 13:30:00 UTC
The fbonetti's answer leads to the proper UTC to Eastern time conversion while accepted David Unric's answer would give wrong time for 8 months in 2017 (while DST is in effect).
Let's look at the following example:
First we'll need to figure out when DST starts/ends in 2017:
As we can see on March 12th, 2017 deep in the night (2:00am) they change time by adding +1 hour, so they "jump" from 1:59:59am up to 3:00:00am instantaneously! Which means there can not be 2:30am on March 12th, 2017.
Let's choose two UTC timestamps - one before and one after that switch, then we will try to convert those two timestamps from UTC back to Eastern.
First timestamp will be safely far enough from the switch moment:
require 'time'
t1 = Time.parse("2017-03-11 15:00:00 +0000")
=> 2017-03-11 15:00:00 +0000
t1_epoch_s = t1.to_i
=> 1489244400
Second timestamp is just +24 hours from the first one:
t2 = Time.parse("2017-03-12 15:00:00 +0000")
=> 2017-03-12 15:00:00 +0000
t2_epoch_s = t2.to_i
=> 1489330800
Now let us convert t1_epoch_s and t2_epoch_s to Eastern:
method-1: by adding Time.zone_offset('EST')
wrong, gives bad result: 10am for both days :(
and offset portion is shown as "+0000" which is also misleading and would refer to completely wrong point in time for people reading our output : ((
Time.at(t1_epoch_s) + Time.zone_offset('EST')
=> 2017-03-11 10:00:00 +0000
Time.at(t2_epoch_s) + Time.zone_offset('EST')
=> 2017-03-12 10:00:00 +0000
method-2: by changing timezone
Good!! Correctly yields 10am and 11am on next day!-)
ENV['TZ'] = 'America/New_York'
Time.at(t1_epoch_s)
=> 2017-03-11 10:00:00 -0500
Time.at(t2_epoch_s)
=> 2017-03-12 11:00:00 -0400
# resetting timezone back
ENV['TZ'] = nil
Basically manually adding Time.zone_offset('EST') is like adding constant and it will give right result for about 4 months (of 12 total) during the year, but then other time you'd have to manually add Time.zone_offset('EDT'), which is another constant. It pretty much same as "a broken clock is right twice a day": )) nasty!
And just for laughter let's see the "slow mo" how proper method handles the actual +1 hour magic jump in time:
ENV['TZ'] = "America/New_York"
Time.at(1489301999 + 0)
=> 2017-03-12 01:59:59 -0500
Time.at(1489301999 + 1)
=> 2017-03-12 03:00:00 -0400
ENV['TZ'] = nil
magic-magic!
In plain ruby, the timezone is determined by the 'TZ' environment variable. You could do something like this:
ENV['TZ'] = 'America/New_York' # set the TZ to Eastern Daylight Time
time = Time.now
time.zone
# => "EDT"
# do stuff
ENV['TZ'] = nil # reset the TZ back to UTC
If you don't mind using a gem,
require 'tzinfo'
tz = TZInfo::Timezone.get('US/Eastern')
Time.now.getlocal(tz.current_period.offset.utc_total_offset)
Credit: https://stackoverflow.com/a/42702906/2441263
I have an AWS server that runs daily cron jobs reporting on our user base. I want to ensure my report is run for the full day the previous day in MST. Currently I use this as the code for the data quering
Time.new(Time.now.year, Time.now.month, Time.now.day).yesterday.beginning_of_day.in_time_zone('MST)..Time.new(Time.now.year, Time.now.month, Time.now.day).yesterday.end_of_day.in_time_zone('MST)
I read it is bad practice to use Time.now as that is the system (UTC) time? I am wondering if what I am doing is a big no no or if there is a more efficient way?
thank you!
Mountain Standard Time is 7 hours behind UTC, so when you capture all the data points from the day of July 22rd in MST, you want the UTC times to be from 7/22 at 7:00AM UTC to 7/23 at 7:00AM UTC.
I don't think your code is correct because you are calling in_time_zone("MST") after beginning_of_day.
When you run this code on a server that is on UTC, the evaluated times are different:
>> Time.new.yesterday.beginning_of_day.in_time_zone('MST').utc
=> 2013-07-22 00:00:00 UTC
>> Time.new.in_time_zone("MST").yesterday.beginning_of_day.utc
=> 2013-07-22 07:00:00 UTC
Here is how you can determine the start and end times properly:
>> t = Time.new
=> 2013-07-23 19:45:10 +0000
>> start_time = t.in_time_zone("MST").yesterday.beginning_of_day
=> Mon, 22 Jul 2013 00:00:00 MST -07:00
>> end_time = t.in_time_zone("MST").yesterday.end_of_day
=> Mon, 22 Jul 2013 23:59:59 MST -07:00
When we convert the start and end times to UTC, we get the desired result.
>> start_time = t.in_time_zone("MST").yesterday.beginning_of_day.utc
=> 2013-07-22 07:00:00 UTC
>> end_time = t.in_time_zone("MST").yesterday.end_of_day.utc
=> 2013-07-23 06:59:59 UTC
I don't know what you are trying to do, but
Time.new(Time.now.year, Time.now.month, Time.now.day)
is definitely a terrible code fragment. For example, if the time lag between the execution time of Time.now.year and that of Time.now.month overlaps the moment of the change of the year, then the time object created with the main Time.new will be neither of the two moments. If you want to get the current time, just do
Time.new
or
Time.now
If you are trying to create a time range calculated out of a single time, then whatever your code should be, create time only once:
t = Time.now
and use that in the rest of your code:
t.some_method..t.some_other_method
I want to be able to parse a Time from a string in Ruby (1.8.7), where the string does not contain any time zone information. I would like to treat the string as though it were in any of a number of time zones specified in this type of format: 'America/New_York'.
Time string example:
'2010-02-05 01:00:01'
I have spent quite a while trying to figure this one out.
I did find a similar question, but its answer does not apply in my case: How do I get Ruby to parse time as if it were in a different time zone?
The problem with the above solution is that my time zones cannot all be represented in the 3-letter format supported by Time.parse (http://www.ruby-doc.org/stdlib-1.8.7/libdoc/time/rdoc/classes/Time.html#M004931).
Is there a good way to accomplish what I'm trying to do here?
Edit: Made my answer actually appear as an answer.
require 'active_support/all'
time = ActiveSupport::TimeZone.new('UTC').parse('2010-02-05 01:00:01')
puts time
puts time.in_time_zone('EST')
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).
You have two options the way I see it. On the one hand you could map the format you wish to use in an array (or any other structure you wish) to the 3-letter format used by Time.parse.
The other option is using the tzinfo gem as specified by my which seems to do the job quite nicely.
>> tz = TZInfo::Timezone.get("America/New_York")
=> #<TZInfo::DataTimezone: America/New_York>
>> tz.now
=> Thu Jul 07 16:29:13 UTC 2011
>> tz = TZInfo::Timezone.get("Europe/Rome")
=> #<TZInfo::DataTimezone: Europe/Rome>
>> tz.now
=> Thu Jul 07 22:30:03 UTC 2011
I'm parsing something like this:
11/23/10 23:29:57
which has no time zone associated with it, but I know it's in the UTC time zone (while I'm not). How can I get Ruby to parse this as if it were in the UTC timezone?
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
credit from https://rubyinrails.com/2018/05/30/rails-parse-date-time-string-in-utc-zone/,
Time.find_zone("UTC").parse(datetime)
# => Wed, 30 May 2018 18:00:00 UTC +05:30
If your using rails you can use the ActiveSupport::TimeZone helpers
current_timezone = Time.zone
Time.zone = "UTC"
Time.zone.parse("Tue Nov 23 23:29:57 2010") # => Tue, 23 Nov 2010 23:29:57 UTC +00:00
Time.zone = current_timezone
It is designed to have the timezone set at the beginning of the request based on user timezone.
Everything does need to have Time.zone on it, so Time.parse would still parse as the servers timezone.
http://api.rubyonrails.org/classes/ActiveSupport/TimeZone.html
Note: the time format you have above was no longer working, so I changed to a format that is supported.
If you are using ActiveSupport [from Rails, e.g], you can do this:
ActiveSupport::TimeZone["GMT"].parse("..... date string")
Another pure Ruby (no Rails) solution if you don't want/need to load ActiveSupport.
require "time"
ENV['TZ'] = 'UTC'
Time.parse("2019/10/01 23:29:57")
#=> 2019-10-01 23:29:57 +0000
An aliter to #Pete Brumm's answer without Time.zone set/unset
Time.zone.parse("Tue Nov 23 23:29:57 2010") + Time.zone.utc_offset
Without rails dependencies: Time parses in local time but DateTime parses in UTC. Then you can transform it to a Time class if that's what you want:
require 'date'
DateTime.parse(string_to_parse).to_time
Rails adds utc method on datetime objects to return the utc time:
Time.parse('10:10').utc