How to obtain first day of next month in ruby?

Question

I have a date of operation. I want create promissory notes which have got:

day=1
month= the next month of operation_date
year= automatic

Example :

operation_date = 15/11/2010 
promissory_note1_date = 1/12/2010
promissory_note2_date = 1/01/2011
promissory_note3_date = 1/02/2011
promissory_note4_date = 1/02/2011

if exist four promissory notes

How could I make it?

PD: Excuse me my syntax

score 203 · Accepted Answer · edited Sep 27 '21 at 14:04

203

You can do

require "active_support"

require "active_support/core_ext/date/calculations"
# || require "active_support/all"

Date.today.at_beginning_of_month
#=> Wed, 01 Dec 2010

Date.today.at_beginning_of_month.next_month
#=> Sat, 01 Jan 2011

Date.today.at_beginning_of_month.next_month.next_month
#=> Tue, 01 Feb 2011

And so on...

References

Rails guide 3.0 - 6.1.4 - ActiveSupport - How to Load Core Extensions
Rails guide 3.0 - 6.1.4 - ActiveSupport - Extensions to date

edited Sep 27 '21 at 14:04

notapatch

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answered Dec 09 '10 at 15:33

jordinl

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`at_beginning_of_month` and so on are provided by ActiveSupport, and are thus available in Rails, but not in pure Ruby. – iGEL Oct 08 '12 at 09:03
4

Just for clarification: this is not pure Ruby but part of the Rails extensions, you need `require "active_support/core_ext"` to make this works – fguillen Mar 16 '13 at 20:30
1

Btw, [`Date.today.beginning_of_month`](https://api.rubyonrails.org/classes/DateAndTime/Calculations.html#method-i-beginning_of_month) works, too. – software_writer Feb 01 '23 at 03:43

score 19 · Answer 2 · answered Dec 09 '16 at 11:07

19

In case you are not using rails or do not wish to require active_support, I found a simpler way without active_support

(Date.today - Date.today.mday + 1) # First day of the current month
=> Thu, 01 Dec 2016

Hope this helps! :-)

answered Dec 09 '16 at 11:07

Sagar Ranglani

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Nice, thanks. And without the +1 it's the last of the previous month, which is also nice :) – bo-oz Jan 07 '17 at 21:51

Jerome · Answer 3 · 2021-04-25T07:57:45.320

12

A response to generically obtain N months (in rails)

(Date.today + N.months).at_beginning_of_month

edited Apr 25 '21 at 07:57

answered Sep 18 '14 at 07:32

Jerome

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A "generic" response which doesn't work in plain Ruby. – Eric Duminil Feb 04 '19 at 10:21

score 8 · Answer 4 · edited Sep 25 '17 at 10:26

8

My solution:

class Time
  def start_of_next_month
    Time.local(self.year + self.month / 12, self.month % 12 + 1)
  end
end

edited Sep 25 '17 at 10:26

Karol Selak

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answered Apr 20 '12 at 14:11

boggy

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score 7 · Answer 5 · edited Jun 23 '14 at 07:33

7

I am using Ruby 1.8.7 and 1.9.2 with rvm and in both cases Date.today results an error:

ruby-1.8.7-p302 > Date.today
NameError: uninitialized constant Date

ruby-1.9.2-p0 > Date.today
NameError: uninitialized constant Object::Date

I thing you should use Time.now and this link should help you http://pleac.sourceforge.net/pleac_ruby/datesandtimes.html .

I am not sure about availability of at_beginning_of_month method in ruby but it does exists in RoR.

edited Jun 23 '14 at 07:33

shybovycha

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answered Dec 09 '10 at 16:00

ranendra

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I've done it in rails console. If you want to use it without rails, you need to require activesupport – jordinl Dec 09 '10 at 16:06
9

ruby-1.8.7-p302 > require 'date' will solve the NameError problem and Date.today will work – ranendra Dec 09 '10 at 16:11
As ravi says, `date` is not fully loaded by default. – tadman Dec 09 '10 at 16:45
Date.today >> n will increment the date by 'n' months. And also Date.today.day and Date.today.month will give you the current date and month. – ranendra Dec 09 '10 at 16:46
at_beginning_of_month will be available to you if you install active_support – Dmitry Feb 04 '14 at 02:50

boggy · Answer 6 · 2011-10-05T14:59:48.477

5

for those working with Time class :

class Time
        def start_of_next_month
                t = Time.local(self.year,self.month)+45*24*3600;
                Time.local(t.year,t.month)
        end
end

I know it's little clumsy :)

edited Oct 05 '11 at 14:59

answered Oct 05 '11 at 14:52

boggy

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Shyam Habarakada · Answer 7 · 2012-04-28T16:43:01.440

3

I wanted to get the first monday of the year (for a rails fixture) and the following worked:

Date.new(Date.today.year,1,1).beginning_of_week

If you aren't in rails, it can be like below,

# get the last day of the previous year
d = Date.new(Date.today.year - 1,12,31)
# advance to the next monday. This relies on w.day being 0..6, where 0 is sunday.
first_monday = d + (8 - d.wday).days

edited Apr 28 '12 at 16:43

answered Apr 28 '12 at 16:29

Shyam Habarakada

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Adam Aiken · Answer 8 · 2018-05-03T12:50:27.410

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As Nov 2017, at_beginning_of_month is no more supported in the latest version. You can use beginning_of_month instead, considering you are using Rails

edited May 03 '18 at 12:50

answered Nov 10 '17 at 05:56

Adam Aiken

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Thanks! And to save the googling for the next person. This is the apidock link for this method as of Rails 6.0.0 https://apidock.com/rails/v6.0.0/DateAndTime/Calculations/beginning_of_month – Jay Killeen Sep 03 '20 at 10:50

score 1 · Answer 9 · answered Dec 05 '16 at 17:18

1

ActiveSupport seems a little heavyweight to load for this. I would do it this way:

require 'date'
first = Date.new(Date.today.year, Date.today.month, 1)
4.times do |m|
  puts "Promissory note due on #{first >> (m + 1)}"
end

answered Dec 05 '16 at 17:18

Mark Reed

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score 0 · Answer 10 · edited Jan 12 '20 at 03:55

 (DateTime.now.beginning_of_year..DateTime.now.end_of_year).to_a.select {|k| k if k == k.beginning_of_month}
=> [Wed, 01 Jan 2020 00:00:00 +0530, Sat, 01 Feb 2020 00:00:00 +0530, Sun, 01 Mar 2020 00:00:00 +0530, Wed, 01 Apr 2020 00:00:00 +0530, Fri, 01 May 2020 00:00:00 +0530, Mon, 01 Jun 2020 00:00:00 +0530, Wed, 01 Jul 2020 00:00:00 +0530, Sat, 01 Aug 2020 00:00:00 +0530, Tue, 01 Sep 2020 00:00:00 +0530, Thu, 01 Oct 2020 00:00:00 +0530, Sun, 01 Nov 2020 00:00:00 +0530, Tue, 01 Dec 2020 00:00:00 +0530]

score 0 · Answer 11 · answered Feb 28 '20 at 15:50

0

This gem extended_date makes it easy, if you are trying it in Rails App. This will help us to get first occurrence of any day in a month

Date.today.first_day_of_month("friday") Date.today.first_day_of_month(5) Date.today.first_day_of_month(0)

answered Feb 28 '20 at 15:50

Prem

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How to obtain first day of next month in ruby?

11 Answers11

References