How can I create a new Date instance in Ruby

Question

How can I create a new Date object in IRB with a given date. The following didn't work.

1.9.3p194 :053 > require 'active_support'
 => true 
1.9.3p194 :054 > Date.new
 => #<Date:0x9d80730> 
1.9.3p194 :055 > Date.parse('12/01/2012')
NoMethodError: undefined method `parse' for Date:Class
        from (irb):55

1.9.3p194 :055 > Date.new('12/01/2012')
ArgumentError: wrong number of arguments(1 for 0)

This http://www.ruby-doc.org/stdlib-1.9.3/libdoc/date/rdoc/Date.html says I should be able to use the methods the way I was trying. — Michael Durrant, Sep 22 '12 at 14:28
You need to `require 'date'` to get the standard library implementation - the core class is a stripped down version. Yes, it is quite confusing. — Lars Haugseth, Sep 22 '12 at 14:35

score 52 · Accepted Answer · edited Apr 14 '20 at 09:30

52

According to Date documentation:

require 'date'

Date.new(2001,2,25)           #=> #<Date: 2001-02-25 
Date.jd(2451966)             #=> #<Date: 2001-02-25 
Date.ordinal(2001,56)        #=> #<Date: 2001-02-25 
Date.commercial(2001,8,7)    #=> #<Date: 2001-02-25 
Date.parse('2001-02-25')     #=> #<Date: 2001-02-25 
Date.strptime('25-02-2001', '%d-%m-%Y') #=> #<Date: 2001-02-25 
Time.new(2001,2,25).to_date   #=> #<Date: 2001-02-25

edited Apr 14 '20 at 09:30

Michael Durrant

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answered Sep 22 '12 at 14:30

Sébastien Le Callonnec

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For those who wonder if the implicit order of the parameters is inspired by American or the rest of the world date ordering, the ordering of the parameters is a logical and neutral ```Date.new(year, month, day)```. – Obromios Jun 01 '17 at 22:58
8

would be so much easier to guess if simply put as `Date.new(2001, 2, 25)` – transGLUKator Aug 14 '17 at 09:18
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Updated from "02-03" to "02-25" per the suggestion :) – Michael Durrant Apr 14 '20 at 09:30

score 4 · Answer 2 · answered Sep 22 '12 at 14:28

4

1.9.3-p125 :012 > require 'date'
 => true 
1.9.3-p125 :013 > Date::new(2012,02,03)
 => #<Date: 2012-02-03 ((2455961j,0s,0n),+0s,2299161j)> 
1.9.3-p125 :014 >

answered Sep 22 '12 at 14:28

Houen

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score 3 · Answer 3 · edited Dec 09 '19 at 15:57

3

I find the following easier to remember than Date.new:

require 'active_support/core_ext/string'
'2019-03-31'.to_date
=> #<Date: 2019-03-21 ((2458564j,0s,0n),+0s,2299161j)>

See https://apidock.com/rails/String/to_date

edited Dec 09 '19 at 15:57

Jon Schneider

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answered Mar 06 '19 at 21:12

jethro

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score 2 · Answer 4 · answered Sep 22 '12 at 14:36

2

If you're trying to get active_support extensions to Date outside of Rails, you'll have to use the core_ext module:

require 'active_support/core_ext/date/calculations'
Date.parse('12/01/2012')
=> #<Date: 2012-01-12 ((2455939j,0s,0n),+0s,2299161j)>

More info in this Rails guide: http://edgeguides.rubyonrails.org/active_support_core_extensions.html

answered Sep 22 '12 at 14:36

rossta

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The standard library Date class supports `parse` too, so no need for ActiveSupport for that. – Lars Haugseth Sep 22 '12 at 14:38

score 0 · Answer 5 · answered Sep 22 '12 at 14:30

0

Date.strptime("2012-09-21 19:45:48","%Y-%m-%d %H:%M:%S")

answered Sep 22 '12 at 14:30

saihgala

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score 0 · Answer 6 · answered Jan 09 '17 at 17:44

You need to use the date extension from the Ruby Standard Library. Most examples in the docs don't always show you to require it.

require 'date'

was what you needed. It's not a built in set of Classes or Modules.

You get two Classes with that addition,

Date
DateTime

And with that you may now use info found in the docs

score 0 · Answer 7 · answered May 29 '17 at 06:31

require 'date'
Date::strptime("29-05-2017", "%d-%m-%Y")

So, you need to include this date module in your code and then use the method strptime inside which you may notice for year, I have used capital Y because full year is entered as the first parameter of the strptime method. You can use small y if the date is like '29-05-17'.

How can I create a new Date instance in Ruby

7 Answers7