Extend the ruby Date class to calculate the week function as MongoDB aggregations calculate the weeks

mongoldb_extend_date.rb

# Purpose: to extend the date class to match the week aggregation for MongoDB 3.2
#

require 'date'

class Date
  def mongo_week_number
    week_offset = 0
    unless Date.new(self.year,1,1).wday == 0
      week_offset = 7 - (Date.new(self.year,1,1).wday)
    end
    week_number = (self.yday.to_f  - week_offset.to_f)/7
    week_number.ceil
  end
  def mongo_week_ending
    self + (6 - self.wday.to_i)
  end
end