I'm trying to parse this date Wed, 17 Feb 2021 13:00:00 +0100 into this 2021-02-17 13:00:00.000000000 +0100.
And I've tried using this Time.strptime(current_time.to_s, '%Q'), (where current_time it's the date above) but I get 1970-01-01 01:00:02.021 +0100
But I don't understand why I get another date, could you help me? Thanks!
I'm trying to parse this date Wed, 17 Feb 2021 13:00:00 +0100 [...]
You seem to already have an instance of Time: (or ActiveSupport::TimeWithZone which is Rails' drop-in replacement with better timezone support)
current_time = Time.current
#=> Thu, 19 May 2022 10:09:58.702560000 CEST +02:00
In this case, there's nothing to parse. You just have to format it via strftime the way you like:
current_time.strftime('%F %T.%N %z')
#=> "2022-05-19 10:09:58.702560000 +0200"
Parsing is only needed when you have a string representation that you want to turn into a Time object, e.g.: (using Rails' Time.zone.parse variant)
time_string = 'Thu, 19 May 2022 10:09:58.702560000 CEST +02:00'
time_obj = Time.zone.parse(time_string)
#=> Thu, 19 May 2022 10:09:58.702560000 CEST +02:00
time_obj.class
#=> ActiveSupport::TimeWithZone
I am trying to convert a date/time string "06/14/2016 07:00 PM" to a Time object under the PST time zone. I want the result to be Tue, 14 Jun 2016 19:00:00 PDT -07:00.
I tried the following:
t = "06/14/2016 07:00 PM"
r = Time.strptime(t, "%m/%d/%Y %I:%M %p").in_time_zone("Pacific Time (US & Canada)")
The time comes back as Tue, 14 Jun 2016 17:00:00 PDT -07:00. Any ideas?
This code to me works properly, but there are two possible issues that are giving you the wrong result:
You are not in the pacific time zone (or at least not according to your computer): You can test this by running r = Time.strptime(t, "%m/%d/%Y %I:%M %p"), and then printing the result of r. I'm willing to wager that it outputs
Tue, 14 Jun 2016 19:00:00 CDT -05:00
You are using ruby and not rails, in_time_zone is a method only in rails. If you try to use it in ruby it will not work.
I'm trying to parse a specific hour of a specific date. When I put the date directly as an argument, it works fine, but when I create a variable and put it in the argument it returns the current date.
Why is that?
NOTE: the variable time is 9pm and I need to parse 9pm of 12 March 2016.
datetime = DateTime.new(2016,3,12,9)
=> Sat, 12 Mar 2016 09:00:00 +0000
DateTime.parse("sat 12 march 2016 9pm")
=> Sat, 12 Mar 2016 21:00:00 +0000
DateTime.parse("datetime 9pm")
=> Mon, 14 Mar 2016 21:00:00 +0000
In your third call, you use the literal string "datetime" rather than the value of your datetime variable. You can use string interpolation to use the variable's value:
DateTime.parse("#{datetime} 9pm")
In this case, the "9pm" is ignored since it doesn't make sense added to the end of an existing date but this is why the initial attempt wasn't working. Interpolation is generally a solution for using a variable's value rather than its name.
If your goal is to change the time of an existing date, use the change method:
datetime.change(hour:21)
You can also try this
date = Date.new(2016,3,12)
DateTime.parse("#{date} 9pm")
## Output
Sat, 12 Mar 2016 21:00:00 +0000
OR
datetime = DateTime.new(2016,3,12,9)
DateTime.parse((datetime + 12.hours).to_s)
## Output
Sat, 12 Mar 2016 21:00:00 +0000
OR
DateTime.parse((datetime + 12.hours).to_s).strftime("%a, %d %b %Y %I:%M %p")
## Output
Sat, 12 Mar 2016 09:00 PM
I need to use .next_week not +1.week. Because the .next_week make the date next week and Monday at the same time. It's so comfortable. And then I subtract some hours. But nothing has been changed. Here's my code.
newDate = DateTime.now
newDate = newDate.next_week - 3.hours
=> Sun, 30 Aug 2015 21:00:00 +0900
newDate = newDate.next_week - 3.hours
=> Sun, 30 Aug 2015 21:00:00 +0900
newDate = newDate.next_week - 3.hours
=> Sun, 30 Aug 2015 21:00:00 +0900
Why they can't be used same time? Please explain to me. Thanks.
This has nothing to do with #next_week and - 3.hours working at the same time. It is a misunderstanding about how #next_week works.
#next_week assumes by default a week is Monday-Sunday. This means when calling just #next_week it will return the next Monday at 00:00:00:00.
Example:
DateTime.now.next_week
#=> Mon, 03 Aug 2015 00:00:00 -0400
Okay so that make sense. Now you are substracting 3.hours making it Sunday again
DateTime.now.next_week - 3.hours
#=> Sun, 02 Aug 2015 21:00:00 -0400
Still makes perfect sense. Now here is where the confusion is. Since you rolled back to Sunday by subtracting 3.hours the #next_week is the following Monday again so
(DateTime.now.next_week - 3.hours).next_week
#=> Mon, 03 Aug 2015 00:00:00 -0400
I hope this helps you understand the situation a bit better.
If you use + 1.week this will take you to the same exact point in time the following week
DateTime.now + 1.week
#=> Fri, 07 Aug 2015 09:01:17 -0400
This does not rely on a weekly calendar but rather the basic math of adding 7 days to the referenced Date object.
In conclusion while #next_week might be comfortable you need to understand what it actually implies and I think I would prefer + 1.week in this case for its flexibility and its lack of assumption.
There are also many other methods for traversing time through ActiveSupport such as #advance, #days_since, weeks_since, etc.
Final note next_week can accept a day parameter as well e.g
DateTime.now.next_week(:tuesday)
#=> Tue, 04 Aug 2015 00:00:00 -0400
DateTime.now.next_week(:thursday)
#=> Thu, 06 Aug 2015 00:00:00 -0400
I have a variable foo that contains a time, lets say 4pm today, but the zone offset is wrong, i.e. it is in the wrong time zone. How do I change the time zone?
When I print it I get
Fri Jun 26 07:00:00 UTC 2009
So there is no offset, and I would like to set the offset to -4 or Eastern Standard Time.
I would expect to be able to just set the offset as a property of the Time object, but that doesn't seem to be available?
You don't explicitly say how you get the actual variable but since you mention the Time class so I'll assume you got the time using that and I'll refer to that in my answer
The timezone is actually part of the Time class (in your case the timezone is shown as UTC). Time.now will return the offset from UTC as part of the Time.now response.
>> local = Time.now
=> 2012-08-13 08:36:50 +0000
>> local.hour
=> 8
>> local.min
=> 36
>>
... in this case I happen to be in the same timezone as GMT
Converting between timezones
The easiest way that I've found is to change the offset using '+/-HH:MM' format to the getlocal method. Let's pretend I want to convert between the time in Dublin and the time in New York
?> dublin = Time.now
=> 2012-08-13 08:36:50 +0000
>> new_york = dublin + Time.zone_offset('EST')
=> 2012-08-13 08:36:50 +0000
>> dublin.hour
=> 8
>> new_york.hour
=> 3
Assuming that 'EST' is the name of the Timezone for New York, as Dan points out sometimes 'EDT' is the correct TZ.
This takes advantage of the fact that Time#asctime doesn't include the zone.
Given a time:
>> time = Time.now
=> 2013-03-13 13:01:48 -0500
Force it to another zone (this returns an ActiveSupport::TimeWithZone):
>> ActiveSupport::TimeZone['US/Pacific'].parse(time.asctime)
=> Wed, 13 Mar 2013 13:01:48 PDT -07:00
Note that the original zone is ignored completely. If I convert the original time to utc, the result will be different:
>> ActiveSupport::TimeZone['US/Pacific'].parse(time.getutc.asctime)
=> Wed, 13 Mar 2013 18:01:48 PDT -07:00
You can use to_time or to_datetime on the result to get a corresponding Time or DateTime.
This question uses an interesting approach with DateTime#change to set the tz offset. (Remember that ActiveSupport makes it easy to convert between Time and DateTime.) The downside is that there's no DST detection; you have to do that manually by using TZInfo's current_period.
If given:
2011-10-25 07:21:35 -700
you want:
2011-10-25 07:21:35 UTC
then do:
Time.parse(Time.now.strftime('%Y-%m-%d %H:%M:%S UTC')).to_s
...
>> Time.at(Time.now.utc + Time.zone_offset('PST'))
=> Mon Jun 07 22:46:22 UTC 2010
>> Time.at(Time.now.utc + Time.zone_offset('PDT'))
=> Mon Jun 07 23:46:26 UTC 2010
>> Time.at(Time.now.utc + Time.zone_offset('CST'))
=> Tue Jun 08 00:46:32 UTC 2010
One note: make sure that the current time object is set to UTC time first, otherwise Ruby will try and convert the Time object to your local timezone, thus throwing the calculation. You can always get the adjusted time by applying ".utc" to the end of the above statements in that case.
For those that came across this while looking for a non-rails solution (as I did), TZInfo solved it for me...
require 'tzinfo'
def adjust_time time, time_zone="America/Los_Angeles"
return TZInfo::Timezone.get(time_zone).utc_to_local(time.utc)
end
puts adjust_time(Time.now)
#=> PST or PDT
puts adjust_time(Time.now, "America/New_York")
#=> EST or EDT
This also handles DST, which is what I needed that wasn't handled above.
See: http://tzinfo.rubyforge.org/
in you environment.rb search for the following line.
# Set Time.zone default to the specified zone and make Active Record auto-convert to this zone.
# Run "rake -D time" for a list of tasks for finding time zone names.
config.time_zone = 'UTC'
Keep in mind ActiveRecord and Rails always handle Time as UTC internally.
I'm using Rails 2.0 before they added the code that makes weppos solution work. Here's what I did
# Silly hack, because sometimes the input_date is in the wrong timezone
temp = input_date.to_time.to_a
temp[8] = true
temp[9] = "Eastern Daylight Time"
input_date = Time.local(*temp)
I break the time down into a 10 element array, change the timezone and then convert the array back into a time.
Here is what worked for me...
def convert_zones(to_zone)
to_zone_time = to_zone.localtime
end
# have your time set as time
time = convert_zones(time)
time.strftime("%b #{day}, %Y (%a) #{hour}:%M %p %Z")
This is what I did, as I am not using Rails and don't want to use any non-core gems.
t = Time.now # my local time - which is GMT
zone_offset = 3600 # offset for CET - which is my target time zone
zone_offset += 3600 if t.dst? # an extra hour offset in summer
time_cet = Time.mktime(t.sec, t.min, t.hour, t.mday, t.mon, t.year, nil, nil, t.dst?, zone_offset)
Option 1
Use date_time_attribute gem:
my_date_time = DateTimeAttribute::Container.new(Time.zone.now)
my_date_time.date_time # => 2001-02-03 22:00:00 KRAT +0700
my_date_time.time_zone = 'Moscow'
my_date_time.date_time # => 2001-02-03 22:00:00 MSK +0400
Option 2
If time is used as an attribute, you can use the same date_time_attribute gem:
class Task
include DateTimeAttribute
date_time_attribute :due_at
end
task = Task.new
task.due_at_time_zone = 'Moscow'
task.due_at # => Mon, 03 Feb 2013 22:00:00 MSK +04:00
task.due_at_time_zone = 'London'
task.due_at # => Mon, 03 Feb 2013 22:00:00 GMT +00:00
It's probably a good idea to store the time as UTC and then show it in a specific time zone when it is displayed. Here's an easy way to do that (works in Rails 4, unsure about earlier versions).
t = Time.now.utc
=> 2016-04-19 20:18:33 UTC
t.in_time_zone("EST")
=> Tue, 19 Apr 2016 15:18:33 EST -05:00
But if you really want to store it in a specific timezone, you can just set the initial Time object to itself.in_time_zone like this:
t = t.in_time_zone("EST")
When Parsing a Time
I'd be interested to hear how you're setting the variable foo to begin with.
If you're parsing a time string that doesn't have a time zone (what I was doing during a data import) then you can use String#in_time_zone to force the time zone during the parsing:
"Fri Jun 26 2019 07:00:00".in_time_zone( "Eastern Time (US & Canada)" )
# => Wed, 26 Jun 2019 07:00:00 EDT -04:00
Works like a charm and is super clean.
You can do:
DateTime.parse('Fri Jun 26 07:00:00 UTC 2009').change(offset: '-0400')
Which returns:
Fri, 26 Jun 2009 07:00:00 -0400