Get time in seconds from string and add to current time? - ruby

Question

timestr = '15h 37m 5s'
I want to get the hours minutes and seconds from the above string and add it to current time.
def next_run
timestr = '15h 37m 5s'
timearr = timestr.split(' ').map { |t| t.to_i }
case timearr.count
when 3
next_ = (timearr[0] * 3600) + (timearr[1] * 60) + timearr[2]
when 2
next_ = (timearr[1] * 60) + timearr[2]
when 1
next_ = timearr[2]
else
raise 'Unknown length for timestr'
end
time_to_run_in_secs = next_
end
Now I get the total seconds. I want to make it into hours minutes and seconds, then add it to current time to get next run time. Is there any easy way to do this?

Answer 1

The following method can be used to compute the the numbers of seconds from the string.
def seconds(str)
3600 * str[/\d+h/].to_i + 60 * str[/\d+m/].to_i + str[/\d+s/].to_i
end
Note nil.to_i #=>0. A slight variant would be to write 3600 * (str[/\d+h/] || 0) +....
Then
Time.now + seconds(str)
Examples of possible values of str are as follows: ”3h 26m 41s”, ”3h 26m”, ”3h 41s”, ”41s 3h”, ”3h”,”41s” and ””.
One could instead write the operative line of the method as follows.
%w| s m h |.each_with_index.sum { |s,i| 60**i * str[/\d+#{s}/].to_i }
Though DRYer, I find that less readable.

Answer 2

DateTime#+ accepts Rational instance as days to be added. All you need as you have seconds would be to convert it to a number of days and plain add to the current timestamp:
DateTime.now.tap do |dt|
break [dt, dt + Rational(100, 3600 * 24) ]
end
#⇒ [
# [0] #<DateTime: 2018-05-27T11:13:00+02:00 ((2458266j,33180s,662475814n),+7200s,2299161j)>,
# [1] #<DateTime: 2018-05-27T11:14:40+02:00 ((2458266j,33280s,662475814n),+7200s,2299161j)>
# ]

Answer 3

you can convert your string into seconds from this method
def seconds(str)
(3600 * str[/\d+(h|H)/].to_i) + (60 * str[/\d+(m|M)/].to_i) + (str[/\d+(s|S)/].to_i)
end
and then convert current time to seconds using method
next_run_time = Time.now.to_i + seconds(<Your Time String>)
now get next run time using
Time.at(next_run_time)
get desired format of time by using strftime method, in your case
Time.at(next_run_time).strftime("%Hh %Mm %Ss")

Answer 4

If you don't need to parse the duration of time, and just want to define it in your code, use ActiveSupport::Duration for readability . (add the gem to your Gemfile, and read the guide on how to use it)
Then you can use it like this:
require 'active_support'
require 'active_support/core_ext/integer'
DURATION = 15.hours + 37.minutes + 5.seconds
# use DURATION.seconds or DURATION.to_i to get the seconds
def next_run
Time.now + DURATION
end
See the API documentation of ActiveSupport::Duration
If you need to define the next run by a user input, it's a good practice to use ISO 8601 to define a duration of time: https://en.wikipedia.org/wiki/ISO_8601#Durations
ISO 8601 durations are parseable:
ActiveSupport::Duration.parse('PT15H37M5S') # => 15 hours, 37 minutes, and 5 seconds (duration)

Answer 5

Firstly instead of spliting the string, you can use Time#parse method. Make sure you have required the library as well.
require 'time'
=> true
Time.parse('15h 37m 5s')
=> 2018-05-27 15:37:05 +0300
This returns a new object of class Time and it has some really useful methods for you - #sec, #min, #hour.
time = Time.parse('15h 37m 5s')
time.sec #=> 5
time.min #=> 37
time.hour #=> 15
Adding adding one Time object to another is pretty straightforward since you can do it only by seconds. A simple solution for the current problem would be:
def next_run
time = Time.parse('15h 37m 5s')
seconds_to_add = time.hour * 3600 + time.min * 60 + time.sec
Time.now + seconds_to_add
end
Hopefully this will answer your question! :)