Class

DateTime

A subclass of Date that easily handles date, hour, minute, second, and offset.

DateTime class is considered deprecated. Use Time class.

DateTime does not consider any leap seconds, does not track any summer time rules.

A DateTime object is created with DateTime::new, DateTime::jd, DateTime::ordinal, DateTime::commercial, DateTime::parse, DateTime::strptime, DateTime::now, Time#to_datetime, etc.

require 'date'

DateTime.new(2001,2,3,4,5,6)
                    #=> #<DateTime: 2001-02-03T04:05:06+00:00 ...>

The last element of day, hour, minute, or second can be a fractional number. The fractional number’s precision is assumed at most nanosecond.

DateTime.new(2001,2,3.5)
                    #=> #<DateTime: 2001-02-03T12:00:00+00:00 ...>

An optional argument, the offset, indicates the difference between the local time and UTC. For example, Rational(3,24) represents ahead of 3 hours of UTC, Rational(-5,24) represents behind of 5 hours of UTC. The offset should be -1 to +1, and its precision is assumed at most second. The default value is zero (equals to UTC).

DateTime.new(2001,2,3,4,5,6,Rational(3,24))
                    #=> #<DateTime: 2001-02-03T04:05:06+03:00 ...>

The offset also accepts string form:

DateTime.new(2001,2,3,4,5,6,'+03:00')
                    #=> #<DateTime: 2001-02-03T04:05:06+03:00 ...>

An optional argument, the day of calendar reform (start), denotes a Julian day number, which should be 2298874 to 2426355 or negative/positive infinity. The default value is Date::ITALY (2299161=1582-10-15).

A DateTime object has various methods. See each reference.

d = DateTime.parse('3rd Feb 2001 04:05:06+03:30')
                    #=> #<DateTime: 2001-02-03T04:05:06+03:30 ...>
d.hour              #=> 4
d.min               #=> 5
d.sec               #=> 6
d.offset            #=> (7/48)
d.zone              #=> "+03:30"
d += Rational('1.5')
                    #=> #<DateTime: 2001-02-04%16:05:06+03:30 ...>
d = d.new_offset('+09:00')
                    #=> #<DateTime: 2001-02-04%21:35:06+09:00 ...>
d.strftime('%I:%M:%S %p')
                    #=> "09:35:06 PM"
d > DateTime.new(1999)
                    #=> true

When should you use DateTime and when should you use Time?

It’s a common misconception that William Shakespeare and Miguel de Cervantes died on the same day in history - so much so that UNESCO named April 23 as World Book Day because of this fact. However, because England hadn’t yet adopted the Gregorian Calendar Reform (and wouldn’t until 1752) their deaths are actually 10 days apart. Since Ruby’s Time class implements a proleptic Gregorian calendar and has no concept of calendar reform there’s no way to express this with Time objects. This is where DateTime steps in:

shakespeare = DateTime.iso8601('1616-04-23', Date::ENGLAND)
 #=> Tue, 23 Apr 1616 00:00:00 +0000
cervantes = DateTime.iso8601('1616-04-23', Date::ITALY)
 #=> Sat, 23 Apr 1616 00:00:00 +0000

Already you can see something is weird - the days of the week are different. Taking this further:

cervantes == shakespeare
 #=> false
(shakespeare - cervantes).to_i
 #=> 10

This shows that in fact they died 10 days apart (in reality 11 days since Cervantes died a day earlier but was buried on the 23rd). We can see the actual date of Shakespeare’s death by using the gregorian method to convert it:

shakespeare.gregorian
 #=> Tue, 03 May 1616 00:00:00 +0000

So there’s an argument that all the celebrations that take place on the 23rd April in Stratford-upon-Avon are actually the wrong date since England is now using the Gregorian calendar. You can see why when we transition across the reform date boundary:

# start off with the anniversary of Shakespeare's birth in 1751
shakespeare = DateTime.iso8601('1751-04-23', Date::ENGLAND)
 #=> Tue, 23 Apr 1751 00:00:00 +0000

# add 366 days since 1752 is a leap year and April 23 is after February 29
shakespeare + 366
 #=> Thu, 23 Apr 1752 00:00:00 +0000

# add another 365 days to take us to the anniversary in 1753
shakespeare + 366 + 365
 #=> Fri, 04 May 1753 00:00:00 +0000

As you can see, if we’re accurately tracking the number of solar years since Shakespeare’s birthday then the correct anniversary date would be the 4th May and not the 23rd April.

So when should you use DateTime in Ruby and when should you use Time? Almost certainly you’ll want to use Time since your app is probably dealing with current dates and times. However, if you need to deal with dates and times in a historical context you’ll want to use DateTime to avoid making the same mistakes as UNESCO. If you also have to deal with timezones then best of luck - just bear in mind that you’ll probably be dealing with local solar times, since it wasn’t until the 19th century that the introduction of the railways necessitated the need for Standard Time and eventually timezones.

Class Methods

Parses the given representation of date and time with the given template, and returns a hash of parsed elements. _strptime does not support specification of flags and width unlike strftime.

See also strptime(3) and strftime.

Creates a DateTime object denoting the given calendar date.

DateTime.new(2001,2,3)    #=> #<DateTime: 2001-02-03T00:00:00+00:00 ...>
DateTime.new(2001,2,3,4,5,6,'+7')
                          #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>
DateTime.new(2001,-11,-26,-20,-55,-54,'+7')
                          #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>

Creates a DateTime object denoting the given week date.

DateTime.commercial(2001) #=> #<DateTime: 2001-01-01T00:00:00+00:00 ...>
DateTime.commercial(2002) #=> #<DateTime: 2001-12-31T00:00:00+00:00 ...>
DateTime.commercial(2001,5,6,4,5,6,'+7')
                          #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>

Creates a new DateTime object by parsing from a string according to some RFC 2616 format.

DateTime.httpdate('Sat, 03 Feb 2001 04:05:06 GMT')
                          #=> #<DateTime: 2001-02-03T04:05:06+00:00 ...>

Raise an ArgumentError when the string length is longer than limit. You can stop this check by passing ‘limit: nil`, but note that it may take a long time to parse.

Creates a new DateTime object by parsing from a string according to some typical ISO 8601 formats.

DateTime.iso8601('2001-02-03T04:05:06+07:00')
                          #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>
DateTime.iso8601('20010203T040506+0700')
                          #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>
DateTime.iso8601('2001-W05-6T04:05:06+07:00')
                          #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>

Raise an ArgumentError when the string length is longer than limit. You can stop this check by passing ‘limit: nil`, but note that it may take a long time to parse.

Creates a DateTime object denoting the given chronological Julian day number.

DateTime.jd(2451944)      #=> #<DateTime: 2001-02-03T00:00:00+00:00 ...>
DateTime.jd(2451945)      #=> #<DateTime: 2001-02-04T00:00:00+00:00 ...>
DateTime.jd(Rational('0.5'))
                          #=> #<DateTime: -4712-01-01T12:00:00+00:00 ...>

Creates a new DateTime object by parsing from a string according to some typical JIS X 0301 formats.

DateTime.jisx0301('H13.02.03T04:05:06+07:00')
                          #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>

For no-era year, legacy format, Heisei is assumed.

DateTime.jisx0301('13.02.03T04:05:06+07:00')
                          #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>

Raise an ArgumentError when the string length is longer than limit. You can stop this check by passing ‘limit: nil`, but note that it may take a long time to parse.

Deserializes JSON string by converting year y, month m, day d, hour H, minute M, second S, offset of and Day of Calendar Reform sg to DateTime.

Creates a DateTime object denoting the given calendar date.

DateTime.new(2001,2,3)    #=> #<DateTime: 2001-02-03T00:00:00+00:00 ...>
DateTime.new(2001,2,3,4,5,6,'+7')
                          #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>
DateTime.new(2001,-11,-26,-20,-55,-54,'+7')
                          #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>

Creates a DateTime object denoting the present time.

DateTime.now              #=> #<DateTime: 2011-06-11T21:20:44+09:00 ...>
No documentation available

Creates a DateTime object denoting the given ordinal date.

DateTime.ordinal(2001,34) #=> #<DateTime: 2001-02-03T00:00:00+00:00 ...>
DateTime.ordinal(2001,34,4,5,6,'+7')
                          #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>
DateTime.ordinal(2001,-332,-20,-55,-54,'+7')
                          #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>

Parses the given representation of date and time, and creates a DateTime object.

This method *does not* function as a validator. If the input string does not match valid formats strictly, you may get a cryptic result. Should consider to use ‘DateTime.strptime` instead of this method as possible.

If the optional second argument is true and the detected year is in the range “00” to “99”, makes it full.

DateTime.parse('2001-02-03T04:05:06+07:00')
                          #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>
DateTime.parse('20010203T040506+0700')
                          #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>
DateTime.parse('3rd Feb 2001 04:05:06 PM')
                          #=> #<DateTime: 2001-02-03T16:05:06+00:00 ...>

Raise an ArgumentError when the string length is longer than limit. You can stop this check by passing ‘limit: nil`, but note that it may take a long time to parse.

Creates a new DateTime object by parsing from a string according to some typical RFC 2822 formats.

DateTime.rfc2822('Sat, 3 Feb 2001 04:05:06 +0700')
                         #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>

Raise an ArgumentError when the string length is longer than limit. You can stop this check by passing ‘limit: nil`, but note that it may take a long time to parse.

Creates a new DateTime object by parsing from a string according to some typical RFC 3339 formats.

DateTime.rfc3339('2001-02-03T04:05:06+07:00')
                          #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>

Raise an ArgumentError when the string length is longer than limit. You can stop this check by passing ‘limit: nil`, but note that it may take a long time to parse.

Creates a new DateTime object by parsing from a string according to some typical RFC 2822 formats.

DateTime.rfc2822('Sat, 3 Feb 2001 04:05:06 +0700')
                         #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>

Raise an ArgumentError when the string length is longer than limit. You can stop this check by passing ‘limit: nil`, but note that it may take a long time to parse.

Parses the given representation of date and time with the given template, and creates a DateTime object. strptime does not support specification of flags and width unlike strftime.

DateTime.strptime('2001-02-03T04:05:06+07:00', '%Y-%m-%dT%H:%M:%S%z')
                          #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>
DateTime.strptime('03-02-2001 04:05:06 PM', '%d-%m-%Y %I:%M:%S %p')
                          #=> #<DateTime: 2001-02-03T16:05:06+00:00 ...>
DateTime.strptime('2001-W05-6T04:05:06+07:00', '%G-W%V-%uT%H:%M:%S%z')
                          #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>
DateTime.strptime('2001 04 6 04 05 06 +7', '%Y %U %w %H %M %S %z')
                          #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>
DateTime.strptime('2001 05 6 04 05 06 +7', '%Y %W %u %H %M %S %z')
                          #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>
DateTime.strptime('-1', '%s')
                          #=> #<DateTime: 1969-12-31T23:59:59+00:00 ...>
DateTime.strptime('-1000', '%Q')
                          #=> #<DateTime: 1969-12-31T23:59:59+00:00 ...>
DateTime.strptime('sat3feb014pm+7', '%a%d%b%y%H%p%z')
                          #=> #<DateTime: 2001-02-03T16:00:00+07:00 ...>

See also strptime(3) and strftime.

No documentation available

Creates a new DateTime object by parsing from a string according to some typical XML Schema formats.

DateTime.xmlschema('2001-02-03T04:05:06+07:00')
                          #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>

Raise an ArgumentError when the string length is longer than limit. You can stop this check by passing ‘limit: nil`, but note that it may take a long time to parse.

Instance Methods

Returns a hash, that will be turned into a JSON object and represent this object.

Returns the hour (0-23).

DateTime.new(2001,2,3,4,5,6).hour         #=> 4

This method is equivalent to strftime(‘%FT%T%:z’). The optional argument n is the number of digits for fractional seconds.

DateTime.parse('2001-02-03T04:05:06.123456789+07:00').iso8601(9)
                          #=> "2001-02-03T04:05:06.123456789+07:00"

Returns a string in a JIS X 0301 format. The optional argument n is the number of digits for fractional seconds.

DateTime.parse('2001-02-03T04:05:06.123456789+07:00').jisx0301(9)
                          #=> "H13.02.03T04:05:06.123456789+07:00"

Returns the minute (0-59).

DateTime.new(2001,2,3,4,5,6).min          #=> 5
An alias for min

Duplicates self and resets its offset.

d = DateTime.new(2001,2,3,4,5,6,'-02:00')
                          #=> #<DateTime: 2001-02-03T04:05:06-02:00 ...>
d.new_offset('+09:00')    #=> #<DateTime: 2001-02-03T15:05:06+09:00 ...>

Returns the offset.

DateTime.parse('04pm+0730').offset        #=> (5/16)

This method is equivalent to strftime(‘%FT%T%:z’). The optional argument n is the number of digits for fractional seconds.

DateTime.parse('2001-02-03T04:05:06.123456789+07:00').rfc3339(9)
                          #=> "2001-02-03T04:05:06.123456789+07:00"

Returns the second (0-59).

DateTime.new(2001,2,3,4,5,6).sec          #=> 6

Returns the fractional part of the second.

DateTime.new(2001,2,3,4,5,6.5).sec_fraction       #=> (1/2)
An alias for sec

Formats date according to the directives in the given format string. The directives begin with a percent (%) character. Any text not listed as a directive will be passed through to the output string.

A directive consists of a percent (%) character, zero or more flags, an optional minimum field width, an optional modifier, and a conversion specifier as follows.

%<flags><width><modifier><conversion>

Flags:

-  don't pad a numerical output.
_  use spaces for padding.
0  use zeros for padding.
^  upcase the result string.
#  change case.
:  use colons for %z.

The minimum field width specifies the minimum width.

The modifiers are “E” and “O”. They are ignored.

Format directives:

Date (Year, Month, Day):
  %Y - Year with century (can be negative, 4 digits at least)
          -0001, 0000, 1995, 2009, 14292, etc.
  %C - year / 100 (round down.  20 in 2009)
  %y - year % 100 (00..99)

  %m - Month of the year, zero-padded (01..12)
          %_m  blank-padded ( 1..12)
          %-m  no-padded (1..12)
  %B - The full month name (``January'')
          %^B  uppercased (``JANUARY'')
  %b - The abbreviated month name (``Jan'')
          %^b  uppercased (``JAN'')
  %h - Equivalent to %b

  %d - Day of the month, zero-padded (01..31)
          %-d  no-padded (1..31)
  %e - Day of the month, blank-padded ( 1..31)

  %j - Day of the year (001..366)

Time (Hour, Minute, Second, Subsecond):
  %H - Hour of the day, 24-hour clock, zero-padded (00..23)
  %k - Hour of the day, 24-hour clock, blank-padded ( 0..23)
  %I - Hour of the day, 12-hour clock, zero-padded (01..12)
  %l - Hour of the day, 12-hour clock, blank-padded ( 1..12)
  %P - Meridian indicator, lowercase (``am'' or ``pm'')
  %p - Meridian indicator, uppercase (``AM'' or ``PM'')

  %M - Minute of the hour (00..59)

  %S - Second of the minute (00..60)

  %L - Millisecond of the second (000..999)
  %N - Fractional seconds digits, default is 9 digits (nanosecond)
          %3N  millisecond (3 digits)   %15N femtosecond (15 digits)
          %6N  microsecond (6 digits)   %18N attosecond  (18 digits)
          %9N  nanosecond  (9 digits)   %21N zeptosecond (21 digits)
          %12N picosecond (12 digits)   %24N yoctosecond (24 digits)

Time zone:
  %z - Time zone as hour and minute offset from UTC (e.g. +0900)
          %:z - hour and minute offset from UTC with a colon (e.g. +09:00)
          %::z - hour, minute and second offset from UTC (e.g. +09:00:00)
          %:::z - hour, minute and second offset from UTC
                                            (e.g. +09, +09:30, +09:30:30)
  %Z - Equivalent to %:z (e.g. +09:00)

Weekday:
  %A - The full weekday name (``Sunday'')
          %^A  uppercased (``SUNDAY'')
  %a - The abbreviated name (``Sun'')
          %^a  uppercased (``SUN'')
  %u - Day of the week (Monday is 1, 1..7)
  %w - Day of the week (Sunday is 0, 0..6)

ISO 8601 week-based year and week number:
The week 1 of YYYY starts with a Monday and includes YYYY-01-04.
The days in the year before the first week are in the last week of
the previous year.
  %G - The week-based year
  %g - The last 2 digits of the week-based year (00..99)
  %V - Week number of the week-based year (01..53)

Week number:
The week 1 of YYYY starts with a Sunday or Monday (according to %U
or %W).  The days in the year before the first week are in week 0.
  %U - Week number of the year.  The week starts with Sunday.  (00..53)
  %W - Week number of the year.  The week starts with Monday.  (00..53)

Seconds since the Unix Epoch:
  %s - Number of seconds since 1970-01-01 00:00:00 UTC.
  %Q - Number of milliseconds since 1970-01-01 00:00:00 UTC.

Literal string:
  %n - Newline character (\n)
  %t - Tab character (\t)
  %% - Literal ``%'' character

Combination:
  %c - date and time (%a %b %e %T %Y)
  %D - Date (%m/%d/%y)
  %F - The ISO 8601 date format (%Y-%m-%d)
  %v - VMS date (%e-%^b-%Y)
  %x - Same as %D
  %X - Same as %T
  %r - 12-hour time (%I:%M:%S %p)
  %R - 24-hour time (%H:%M)
  %T - 24-hour time (%H:%M:%S)
  %+ - date(1) (%a %b %e %H:%M:%S %Z %Y)

This method is similar to the strftime() function defined in ISO C and POSIX. Several directives (%a, %A, %b, %B, %c, %p, %r, %x, %X, %E*, %O* and %Z) are locale dependent in the function. However, this method is locale independent. So, the result may differ even if the same format string is used in other systems such as C. It is good practice to avoid %x and %X because there are corresponding locale independent representations, %D and %T.

Examples:

d = DateTime.new(2007,11,19,8,37,48,"-06:00")
                          #=> #<DateTime: 2007-11-19T08:37:48-0600 ...>
d.strftime("Printed on %m/%d/%Y")   #=> "Printed on 11/19/2007"
d.strftime("at %I:%M%p")            #=> "at 08:37AM"

Various ISO 8601 formats:

%Y%m%d           => 20071119                  Calendar date (basic)
%F               => 2007-11-19                Calendar date (extended)
%Y-%m            => 2007-11                   Calendar date, reduced accuracy, specific month
%Y               => 2007                      Calendar date, reduced accuracy, specific year
%C               => 20                        Calendar date, reduced accuracy, specific century
%Y%j             => 2007323                   Ordinal date (basic)
%Y-%j            => 2007-323                  Ordinal date (extended)
%GW%V%u          => 2007W471                  Week date (basic)
%G-W%V-%u        => 2007-W47-1                Week date (extended)
%GW%V            => 2007W47                   Week date, reduced accuracy, specific week (basic)
%G-W%V           => 2007-W47                  Week date, reduced accuracy, specific week (extended)
%H%M%S           => 083748                    Local time (basic)
%T               => 08:37:48                  Local time (extended)
%H%M             => 0837                      Local time, reduced accuracy, specific minute (basic)
%H:%M            => 08:37                     Local time, reduced accuracy, specific minute (extended)
%H               => 08                        Local time, reduced accuracy, specific hour
%H%M%S,%L        => 083748,000                Local time with decimal fraction, comma as decimal sign (basic)
%T,%L            => 08:37:48,000              Local time with decimal fraction, comma as decimal sign (extended)
%H%M%S.%L        => 083748.000                Local time with decimal fraction, full stop as decimal sign (basic)
%T.%L            => 08:37:48.000              Local time with decimal fraction, full stop as decimal sign (extended)
%H%M%S%z         => 083748-0600               Local time and the difference from UTC (basic)
%T%:z            => 08:37:48-06:00            Local time and the difference from UTC (extended)
%Y%m%dT%H%M%S%z  => 20071119T083748-0600      Date and time of day for calendar date (basic)
%FT%T%:z         => 2007-11-19T08:37:48-06:00 Date and time of day for calendar date (extended)
%Y%jT%H%M%S%z    => 2007323T083748-0600       Date and time of day for ordinal date (basic)
%Y-%jT%T%:z      => 2007-323T08:37:48-06:00   Date and time of day for ordinal date (extended)
%GW%V%uT%H%M%S%z => 2007W471T083748-0600      Date and time of day for week date (basic)
%G-W%V-%uT%T%:z  => 2007-W47-1T08:37:48-06:00 Date and time of day for week date (extended)
%Y%m%dT%H%M      => 20071119T0837             Calendar date and local time (basic)
%FT%R            => 2007-11-19T08:37          Calendar date and local time (extended)
%Y%jT%H%MZ       => 2007323T0837Z             Ordinal date and UTC of day (basic)
%Y-%jT%RZ        => 2007-323T08:37Z           Ordinal date and UTC of day (extended)
%GW%V%uT%H%M%z   => 2007W471T0837-0600        Week date and local time and difference from UTC (basic)
%G-W%V-%uT%R%:z  => 2007-W47-1T08:37-06:00    Week date and local time and difference from UTC (extended)

See also strftime(3) and ::strptime.

Returns a Date object which denotes self.

Returns self.

Stores class name (DateTime) with Julian year y, month m, day d, hour H, minute M, second S, offset of and Day of Calendar Reform sg as JSON string

Returns a string in an ISO 8601 format. (This method doesn’t use the expanded representations.)

DateTime.new(2001,2,3,4,5,6,'-7').to_s
                         #=> "2001-02-03T04:05:06-07:00"

Returns a Time object which denotes self.

Returns the timezone.

DateTime.parse('04pm+0730').zone          #=> "+07:30"