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.

Same as DateTime.new.

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.

See as_json.

Same as DateTime.new.

Creates a DateTime object denoting the present time.

DateTime.now              #=> #<DateTime: 2011-06-11T21:20:44+09:00 ...>

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.

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

Methods DateTime#as_json and DateTime.json_create may be used to serialize and deserialize a DateTime object; see Marshal.

Method DateTime#as_json serializes self, returning a 2-element hash representing self:

require 'json/add/datetime'
x = DateTime.now.as_json
# => {"json_class"=>"DateTime", "y"=>2023, "m"=>11, "d"=>21, "sg"=>2299161.0}

Method JSON.create deserializes such a hash, returning a DateTime object:

DateTime.json_create(x) # BUG? Raises Date::Error "invalid date"

Returns a hash of the name/value pairs, to use in pattern matching. Possible keys are: :year, :month, :day, :wday, :yday, :hour, :min, :sec, :sec_fraction, :zone.

Possible usages:

dt = DateTime.new(2022, 10, 5, 13, 30)

if d in wday: 1..5, hour: 10..18  # uses deconstruct_keys underneath
  puts "Working time"
end
#=> prints "Working time"

case dt
in year: ...2022
  puts "too old"
in month: ..9
  puts "quarter 1-3"
in wday: 1..5, month:
  puts "working day in month #{month}"
end
#=> prints "working day in month 10"

Note that deconstruction by pattern can also be combined with class check:

if d in DateTime(wday: 1..5, hour: 10..18, day: ..7)
  puts "Working time, first week of the month"
end

Returns the hour in range (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 in range (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 in range (0..59):

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

Returns the fractional part of the second in range (Rational(0, 1)…Rational(1, 1)):

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

Returns a string representation of self, formatted according the given +format:

DateTime.now.strftime # => "2022-07-01T11:03:19-05:00"

For other formats, see Formats for Dates and Times:

Returns a Date object which denotes self.

Returns self.

Returns a JSON string representing self:

require 'json/add/datetime'
puts DateTime.now.to_json

Output:

{"json_class":"DateTime","y":2023,"m":11,"d":21,"sg":2299161.0}

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"