Ruby TZInfo and Rails ActiveSupport::Timezone UTC_offset differences - ruby-on-rails

I want to find the total UTC offset from a Timezone Object. Below are two examples using TZInfo::Timezone and ActiveSupport::TimeZone. Ultimately, I want to use the ActiveSupport::TimeZone implementation, but can't get it to give me the right answer.
#TZInfo implementation
tz = TZInfo::Timezone.get('America/New_York')
tz.current_period.utc_total_offset / 60 / 60
=> -4 (CORRECT)
# Rails implementation
tz = ActiveSupport::TimeZone.new("Eastern Time (US & Canada)")
tz.utc_offset / 60 / 60
=> -5 (WRONG)
Why does ActiveSupport::TimeZone appear to fail to factor in dst? How do I fix that?

I found this in the ActiveSupport documentation. Basically, it is running tzinfo.current_period.utc_offset instead of tzinfo.current_period.utc_total_offset
def utc_offset
if #utc_offset
#utc_offset
else
tzinfo.current_period.utc_offset if tzinfo && tzinfo.current_period
end
end
So to fully answer my question: I need the following code...
tz = ActiveSupport::TimeZone.new("Eastern Time (US & Canada)")
tz.tzinfo.current_period.utc_total_offset / 60 / 60

Related

How to output days as hours in Ruby on Rails?

In my Ruby on Rails application I have a constant like this:
TIME = 3.days
Is there a way to output this value in hours?
# => 72
Thanks for any help.
Ruby or Rails has no direct method for this but if you google you can find a lot of way to do this.you can try followings:
3.days/1.hour
also take a look at Is there any method in Rails to convert minutes as integer to days, months, etc
> 3.days / 3600
=> 72
Not very intuitive, I know.
TIME = 3.days
=> 259200
TIME/3600
=> 72
We have to covert it in hours (60 * 60 = 3600) :P
in_hours (Rails 6.1+)
Rails 6.1 introduces new ActiveSupport::Duration conversion methods like in_seconds, in_minutes, in_hours, in_days, in_weeks, in_months, and in_years.
As a result, now, your problem can be solved as simple as:
3.days.in_hours
# => 72.0
Here is a link to the corresponding PR.

Finding out if any time zone is in midnight currently

I am working on scheduler module, for which I want to know if any X time zone is in midnight currently. Is there any library/gem for this purpose? If not, what would be a good logic to find out?
Your phrasing is a little ambiguous ("any X time zone"), so I'll address another possible interpretation:
If you'd like to check whether "it's midnight somewhere", with "midnight" understood broadly to mean any time from 00:00 to 00:59, a simple one-liner is
ActiveSupport::TimeZone.all.any?{ |time| time.now.hour.zero? }
To check that it's precisely 00:00 (or 00:00:00, although I can't imagine why you would want to do that...), add the appropriate conditions to the boolean block:
ActiveSupport::TimeZone.all.any?{ |time| time.now.hour.zero? && time.now.min.zero? }
You can probably leave off the ActiveSupport:: when calling TimeZone.all from within your Rails app.
[source]
You could do this:
> Time.zone
=> (GMT-05:00) Eastern Time (US & Canada)
> given_time_zone = "Central Time (US & Canada)"
> Time.zone.now.in_time_zone(given_time_zone)
=> Sun, 23 Mar 2014 23:55:57 CDT -05:00
Then you could check if the hour is zero to check if it's within 12 midnight till 1AM:
> Time.zone.now.in_time_zone(given_time_zone).hour == 0
=> false

convert with rails time helpers

Rails offers helpers like 24.hours, 1.minute etc. How can I get the number of minutes in 1.hour?
One option, if you want to stick with the 1.hour style language, is to divide by a single "minute":
1.hour / 1.minute
# => 60
5.hours / 1.minute
# => 300
n.minutes or n.hours are numerically kept in the form of seconds so to convert in minutes try this
hour_in_minutes = 1.hour/60
Try
1.hours/1.minute
At the end, 1.hours, etc. is just a Fixnum
1.hour.minutes will return 60 minutes.

Convert duration to hours:minutes:seconds (or similar) in Rails 3 or Ruby

I have a feeling there is a simple/built-in way to do this but I can't find it.
I have a duration (in seconds) in an integer and I want to display it in a friendly format.
e.g. 3600 would be displayed as "01:00:00" or "1 hour" or something.
I can do it with time_ago_in_words(Time.zone.now+3600) but that feels like a bit of a hack, there is no reason to add/subtract from the current time just to format this value. Is there a duration_in_words() or something?
Thanks
Summing up:
assuming that total_seconds = 3600
Option 1:
distance_of_time_in_words(total_seconds) #=> "about 1 hour"
Option 2:
Time.at(total_seconds).utc.strftime("%H:%M:%S") #=> "01:00:00"
Note: it overflows, eg. for total_seconds = 25.hours.to_i it'll return "01:00:00" also
Option 3:
seconds = total_seconds % 60
minutes = (total_seconds / 60) % 60
hours = total_seconds / (60 * 60)
format("%02d:%02d:%02d", hours, minutes, seconds) #=> "01:00:00"
Option 4:
ActiveSupport::Duration.build(total_seconds).inspect #=> "1 hour"
# OR
parts = ActiveSupport::Duration.build(total_seconds).parts
"%02d:%02d:%02d" % [parts.fetch(:hours, 0),
parts.fetch(:minutes, 0),
parts.fetch(:seconds, 0)] #=> "01:00:00"
See: http://api.rubyonrails.org/classes/ActionView/Helpers/DateHelper.html
distance_of_time_in_words(3600)
=> "about 1 hour"
Ruby's string % operator is too unappreciated and oft forgotten.
"%02d:%02d:%02d:%02d" % [t/86400, t/3600%24, t/60%60, t%60]
Given t is a duration in seconds, this emits a zero-padded colon-separated string including days. Example:
t = 123456
"%02d:%02d:%02d:%02d" % [t/86400, t/3600%24, t/60%60, t%60]
=> "01:10:17:36"
Lovely.
I guess you could do also something like:
(Time.mktime(0)+3600).strftime("%H:%M:%S")
To format it as you wish.
BTW, originally I thought of using Time.at() but seems that EPOCH time on my Ubuntu is Thu Jan 01 01:00:00 +0100 1970 and not 00:00:00 hours as I expected, and therefore if I do:
Time.at(3600).strftime("%H:%M:%S")
Gives me 1 hour more than wanted.
I use this to show time durations in my Rails Project:
Add a custom method to the Integer class. You can create a new file called pretty_duration.rb in the initializers folder:
class Integer
def pretty_duration
parse_string =
if self < 3600
'%M:%S'
else
'%H:%M:%S'
end
Time.at(self).utc.strftime(parse_string)
end
end
Call seconds.pretty_duration anywhere in your project:
275.pretty_duration # => "04:35"
9823.pretty_duration # => "02:43:43"
This answer builds up on Lev Lukomsky's Code
This one uses the obscure divmod method to divide and modulo at the same time, so it handles Float seconds properly:
def duration(seconds)
minutes, seconds = seconds.divmod(60)
hours, minutes = minutes.divmod(60)
days, hours = hours.divmod(24)
"#{days.to_s.rjust(3)}d #{hours.to_s.rjust(2)}h #{minutes.to_s.rjust(2)}m #{seconds}s"
end
ActiveSupport::Duration.build + inspect gives you valid results
>> ActiveSupport::Duration.build(125557).inspect
=> "1 day, 10 hours, 52 minutes, and 37 seconds"
Using Time.utc.strftime works only for values when total number of hours is less then 24:
2.2.2 :004 > Time.at(60 * 60).utc.strftime('%H h %M m')
=> "01 h 00 m"
For greater values it returns incorrect results:
2.2.2 :006 > Time.at(60 * 60 * 24).utc.strftime('%H h %M m')
=> "00 h 00 m"
I suggest using the simplest method I found for this problem:
def formatted_duration total_seconds
hours = total_seconds / (60 * 60)
minutes = (total_seconds / 60) % 60
seconds = total_seconds % 60
"#{ hours } h #{ minutes } m #{ seconds } s"
end
You can always adjust returned value to your needs.
Be careful with the duration longer than one day.
(timing/3600).to_i.to_s.rjust(2,'0') + ":"+Time.at(timing).utc.strftime("%M:%S")
An answer inspired from Lev Lukomsky's one taking advantage of ActiveSupport::Duration, and handling milliseconds (useful to benchmark code)
# duration in ms modulus number of ms in one second
milliseconds = duration.in_milliseconds % 1.second.in_milliseconds
# duration in seconds modulus number of seconds in one minute
seconds = (duration / 1.second) % (1.minute / 1.second)
# duration in minutes modulus number of minutes in one hour
minutes = (duration / 1.minute) % (1.hour / 1.minute)
# duration in hours modulus number of hours in one day
hours = (duration / 1.hour) % (1.day / 1.hour)
format("%02d:%02d:%02d:%03d", hours, minutes, seconds, milliseconds) #=> "12:05:00:001"
Of course you can extend this easily with days, months, years, etc using related ActiveSupport methods and repeating the same structure.
Keep in mind that for too long durations, this may be inaccurate since the duration of 1 month is not fixed in number of days, and I'm not sure how AS:Duration deals with that.
Shout out to #joshuapinter who gave the best answer (in the form of a comment).
Use the drop-in replacement dotiw gem to gain more control over the accuracy of the output to suit different needs:
https://github.com/radar/distance_of_time_in_words
Sample view code:
%label
Logoff after:
- expire_in = distance_of_time_in_words(Time.now, Time.now + user.custom_timeout.minutes, :only => [:minutes, :hours, :days])
= expire_in
Resulting in something like this:
Logoff after: 1 day, 13 hours, and 20 minutes
Just to throw in my 2 cents:
Time.at(i).utc.strftime((i < 3600) ? '%-M minutes and %-S seconds' : '%-H hours, %-M minutes, and %-S seconds')
Built off of Xiao Bin's answer.
Here a simple solution using divmod and map:
hours = 3.5456
value = (hours*60).divmod(60).map{ |a| "%02d"%[a.floor] }.join(":")
=> "03:32"

How do I get the number of seconds between two DateTimes in Ruby on Rails

I've got code that does time tracking for employees. It creates a counter to show the employee how long they have been clocked in for.
This is the current code:
start_time = Time.parse(self.settings.first_clock_in)
total_seconds = Time.now - start_time
hours = (total_seconds/ 3600).to_i
minutes = ((total_seconds % 3600) / 60).to_i
seconds = ((total_seconds % 3600) % 60).to_i
This works fine. But because Time is limited to the range of 1970 - 2038 we are trying to replace all Time uses with DateTimes. I can't figure out how to get the number of seconds between two DateTimes. Subtracting them yields a Rational which I don't know how to interpret, whereas subtracting Times yields the difference in seconds.
NOTE: Since Ruby 1.9.2, the hard limit of Time is removed. However, Time is optimized for values between 1823-11-12 and 2116-02-20.
Subtracting two DateTimes returns the elapsed time in days, so you could just do:
elapsed_seconds = ((end_time - start_time) * 24 * 60 * 60).to_i
Or, more readably:
diff = datetime_1 - datetime_2
diff * 1.days # => difference in seconds; requires Ruby on Rails
Note, what you or some other searchers might really be looking for is this:
diff = datetime_1 - datetime_2
Date.day_fraction_to_time(diff) # => [h, m, s, frac_s]
You can convert them to floats with to_f, though this will incur the usual loss of precision associated with floats. If you're just casting to an integer for whole seconds it shouldn't be big enough to be a worry.
The results are in seconds:
>> end_time.to_f - start_time.to_f
=> 7.39954495429993
>> (end_time.to_f - start_time.to_f).to_i
=> 7
Otherwise, you could look at using to_formatted_s on the DateTime object and seeing if you can coax the output into something the Decimal class will accept, or just formatting it as plain Unix time as a string and calling to_i on that.
Others incorrectly rely on fractions or helper functions. It's much simpler than that. DateTime itself is integer underneath. Here's the Ruby way:
stop.to_i - start.to_i
Example:
start = Time.now
=> 2016-06-21 14:55:36 -0700
stop = start + 5.seconds
=> 2016-06-21 14:55:41 -0700
stop.to_i - start.to_i
=> 5
I am using ruby-2.1.4 and for me the following worked
Time.now - Time.new(2014,11,05,17,30,0)
gave me the time difference in seconds
reference: ruby doc
there's a method made for that:
Time.now.minus_with_coercion(10.seconds.ago)
equals 10.
Source: http://apidock.com/rails/Time/minus_with_coercion
Hope I helped.
Define a Ruby function like this,
def time_diff(start_time, end_time)
seconds_diff = (start_time - end_time).to_i.abs
days = seconds_diff / 86400
seconds_diff -= days * 86400
hours = seconds_diff / 3600
seconds_diff -= hours * 3600
minutes = seconds_diff / 60
seconds_diff -= minutes * 60
seconds = seconds_diff
"#{days} Days #{hours} Hrs #{minutes} Min #{seconds} Sec"
end
And Call this function,
time_diff(Time.now, Time.now-4.days-2.hours-1.minutes-53.seconds)

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