Is it possible to create a list of months between two dates in Rails

Question

I am trying to create a page to display a list of links for each month, grouped into years. The months need to be between two dates, Today, and The date of the first entry.<

Answer 1

Use the date_helper gem which adds the months_between method to the Date class similar to Steve's answer.

xmas = Date.parse("2013-12-25")
hksar_establishment_day = Date.parse("2014-07-01")

Date.months_between(xmas,hksar_establishment_day)
 => [Sun, 01 Dec 2013, Wed, 01 Jan 2014, Sat, 01 Feb 2014, Sat, 01 Mar 2014, Tue, 01 Apr 2014, Thu, 01 May 2014, Sun, 01 Jun 2014, Tue, 01 Jul 2014]

Answer 2

The following code will add a months_between instance method to the Date class

#!/usr/bin/ruby 

require 'date'

class Date

  def self.months_between(d1, d2)
    months = []
    start_date = Date.civil(d1.year, d1.month, 1)
    end_date = Date.civil(d2.year, d2.month, 1)

    raise ArgumentError unless d1 <= d2

    while (start_date < end_date)
      months << start_date
      start_date = start_date >>1
    end

    months << end_date

  end
end

This is VERY lightly tested, however it returns an Array of dates each date being the 1st day in each affected month.

Answer 3

Just put what you want inside a range loop and use the Date::MONTHNAMES array like so

(date.year..laterdate.year).each do |y|
   mo_start = (date.year == y) ? date.month : 1
   mo_end = (laterdate.year == y) ? laterdate.month : 12

   (mo_start..mo_end).each do |m|  
       puts Date::MONTHNAMES[m]
   end
end

Answer 4

I don't know if I've completely understood your problem, but some of the following might be useful. I've taken advantage of the extensions to Date provided in ActiveSupport:

d1 = Date.parse("20070617") # => Sun, 17 Jun 2007
d2 = Date.parse("20090529") #=> Fri, 29 May 2009
eom = d1.end_of_month #=> Sat, 30 Jun 2007
mth_ends = [eom] #=> [Sat, 30 Jun 2007]
while eom < d2
  eom = eom.advance(:days => 1).end_of_month
  mth_ends << eom
end
yrs = mth_ends.group_by{|me| me.year}

The final line uses another handy extension: Array#group_by, which does pretty much exactly what it promises.

d1.year.upto(d2.year) do |yr|
  puts "#{yrs[yr].min}, #{yrs[yr].max}"
end
2007-06-30, 2007-12-31
2008-01-31, 2008-12-31
2009-01-31, 2009-05-31

I don't know if the start/end points are as desired, but you should be able to figure out what else you might need.

HTH