Ruby on Rails 3 Time - Parse Milliseconds - ruby-on-rails

Question

I'm trying to parse a date like: 2011-05-21 04:20:46.011 into a Time object in Rails. So far I have the following:
Time.strptime("2011-05-21 04:20:46.011", "%Y-%m-%d %H:%M:%S.%3N")
But it doesn't seem to like the "%3N" at the end. How do I parse this date?

Answer 1

Use parse:
x = Time.parse("2011-05-21 04:20:46.011", "%Y-%m-%d %H:%M:%S.%3N")
# => 2011-05-21 04:20:46 -0700
x.usec
# => 11000
In many case you don't need to pass in the format either:
x = Time.parse("2011-05-21 04:20:46.011")
# => 2011-05-21 04:20:46 -0700
x.usec
# => 11000

Answer 2

Try Time.parse("2011-05-21 04:20:46.011", "%Y-%m-%d %H:%M:%S.%3N")

Answer 3

With Ruby v 2.3.2 and Rails v 5.0.0.1 in rails console
2.3.2 :035 > Time.parse("2011-05-21 04:20:46.011", "%Y-%m-%d %H:%M:%S.%3N")
NoMethodError: undefined method `getlocal' for "%Y-%m-%d %H:%M:%S.%3N":String
from /home/jignesh/.rvm/rubies/ruby-2.3.2/lib/ruby/2.3.0/time.rb:264:in `make_time'
from /home/jignesh/.rvm/rubies/ruby-2.3.2/lib/ruby/2.3.0/time.rb:366:in `parse'
from (irb):35
Note: In code below in the parse format, NOT prefixed %N with the number of fractional digits like %3N and instead simply specified %N and it works
2.3.2 :037 > Time.strptime("2011-05-21 04:20:46.011", "%Y-%m-%d %H:%M:%S.%N")
=> 2011-05-21 04:20:46 +0530
2.3.2 :038 > tt = Time.strptime("2011-05-21 04:20:46.011", "%Y-%m-%d %H:%M:%S.%N")
=> 2011-05-21 04:20:46 +0530
2.3.2 :039 > tt.usec
=> 11000
The above code didn't worked when using parse
2.3.2 :040 > tt = Time.parse("2011-05-21 04:20:46.011", "%Y-%m-%d %H:%M:%S.%N")
NoMethodError: undefined method `getlocal' for "%Y-%m-%d %H:%M:%S.%N":String
from /home/jignesh/.rvm/rubies/ruby-2.3.2/lib/ruby/2.3.0/time.rb:264:in `make_time'
from /home/jignesh/.rvm/rubies/ruby-2.3.2/lib/ruby/2.3.0/time.rb:366:in `parse'
from (irb):40
It looks strange because Time.strptime(date, format, now=self.now) official documentation does mention about %3N, %6N and %9N explicitly and using them in the parse format doesn't work!
Rails does provide a counterpart strptime(str, format, now=now()) as part of ActiveSupport::TimeZone API and it internally does the parsing using Ruby's standard DateTime._strptime as shown in its source-code:
# File activesupport/lib/active_support/values/time_zone.rb, line 382
def strptime(str, format, now=now())
parts_to_time(DateTime._strptime(str, format), now)
end
And I guess DateTime._strptime internally delegates to Ruby's standard Time.strptime
For those who are looking for leveraging Rails's Time.zone.parse counterpart for parsing in a specific format they can use below code:
tt = Time.zone.strptime('1999-12-31 14:00:00.011111', '%Y-%m-%d %H:%M:%S.%N')
=> Fri, 31 Dec 1999 14:00:00 UTC +00:00
2.3.2 :031 > tt.usec
=> 11111
Hope someone from the core-team can clarify about this behaviour observed and if the behaviour is normal then at-least a note should be made about in the documentation.