Is there an add_days in ruby datetime?

Question

In C#, There is a method AddDays([number of days]) in DateTime class.

Is there any kind of method like this in ruby?

Answer 1

The Date class provides a + operator that does just that.

>> d = Date.today
=> #<Date: 4910149/2,0,2299161>
>> d.to_s
=> "2009-08-31"
>> (d+3).to_s
=> "2009-09-03"
>> 

Answer 2

From the Date class:

+(n)

Return a new Date object that is n days later than the current one.

n may be a negative value, in which case the new Date is earlier than the current one; however, #-() might be more intuitive.

If n is not a Numeric, a TypeError will be thrown. In particular, two Dates cannot be added to each other.

Answer 3

Date.new(2001,9,01).next_day(30) # 30 - numbers of day 
# => #<Date: 2001-10-01 ...

Answer 4

In Rails there are very useful methods of Fixnum class for this (here n is Fixnum. For example: 1,2,3.... ):

Date.today + n.seconds # you can use 1.second
Date.today + n.minutes # you can use 1.minute
Date.today + n.hours # you can use 1.hour
Date.today + n.days # you can use 1.day
Date.today + n.weeks # you can use 1.week
Date.today + n.months # you can use 1.month
Date.today + n.years # you can use 1.year

These are convenient for Time class too.

PS: require Active Support Core Extensions to use these in Ruby

require 'active_support/core_ext'

Answer 5

You can also use the advance (https://apidock.com/rails/DateTime/advance) method. I think it's more legible.

date = Date.today
# => Fri, 25 Oct 2019
date.advance(days: 10)
# => Mon, 04 Nov 2019

time = DateTime.now
# => Fri, 25 Oct 2019 14:32:53 +0200
time.advance(months:1, weeks: 2, days: 2, hours: 6, minutes: 6, seconds: 34)
# => Wed, 11 Dec 2019 20:39:27 +0200

Answer 6

I think next_day is more readable than + version.

require 'date'

DateTime.new(2016,5,17)
# => #<DateTime: 2016-05-17T00:00:00+00:00 ((2457526j,0s,0n),+0s,2299161j)>
DateTime.new(2016,5,17).next_day(10)
# => #<DateTime: 2016-05-27T00:00:00+00:00 ((2457536j,0s,0n),+0s,2299161j)>
Date.new(2016,5,17)
# => #<Date: 2016-05-17 ((2457526j,0s,0n),+0s,2299161j)>
Date.new(2016,5,17).next_day(10)
# => #<Date: 2016-05-27 ((2457536j,0s,0n),+0s,2299161j)>

http://ruby-doc.org/stdlib-2.3.1/libdoc/date/rdoc/Date.html#method-i-next_day.