Get the first Monday of every quarter in Rails

user_14631054 0
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What is the cleanest way to get the first Monday of every quarter of the year in Ruby on Rails?

The solutions i found looks terrible to me: Check if today is one of the first 7 days of the month, then check if today is Monday and finally look if this month is included in one of the 4 months of the quarter.

I think it should be a better way to accomplish this.

quarter date ruby-on-rails ruby
2 Answers

Here's my approach:

first_day = Date.today.beginning_of_year
mondays = 4.times.map do |i|
  first_day_of_quarter = first_day.advance(months: 3 * i).beginning_of_quarter
  first_day_of_quarter.monday? ? first_day_of_quarter : first_day_of_quarter.next_week
end

# [0] Mon, 04 Jan 2021,
# [1] Mon, 05 Apr 2021,
# [2] Mon, 05 Jul 2021,
# [3] Mon, 04 Oct 2021
user_33595770

Here is a pure-Ruby solution.

def first_monday_by_quarter(year)
  [1, 4, 7, 10].map do |month|
    d = Date.new(year, month, 1)
    d.wday.zero? ? (d+1) : d+8-d.wday
  end
end

first_monday_by_quarter(2022)
  #=> [#<Date: 2022-01-03 ((2459583j,0s,0n),+0s,2299161j)>,
  #    #<Date: 2022-04-04 ((2459674j,0s,0n),+0s,2299161j)>,
  #    #<Date: 2022-07-04 ((2459765j,0s,0n),+0s,2299161j)>,
  #    #<Date: 2022-10-03 ((2459856j,0s,0n),+0s,2299161j)>]

first_monday_by_quarter(Date.today.year)
  #=> #<Date: 2021-01-04 ((2459219j,0s,0n),+0s,2299161j)>,
  #   #<Date: 2021-04-05 ((2459310j,0s,0n),+0s,2299161j)>,
  #   #<Date: 2021-07-05 ((2459401j,0s,0n),+0s,2299161j)>,
  #   #<Date: 2021-10-04 ((2459492j,0s,0n),+0s,2299161j)>]

If desired, one could shorten Date.new(year, month, 1) to Date.new(year, month). require 'date' would be needed if this were used in pure-Ruby code.

user_2569700
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