Mask days of week into binary, save to integer field

days_week_masking.rb

DAYS = %w[0 1 2 3 4 5 6 7]
DAYS_HUMAN = %w[Sun Mon Tue Wed Thur Fri Sat]

def days=(days)
  self.days_mask = (days & DAYS).map { |r| 2**DAYS.index(r) }.sum
end

def days
  DAYS.reject do |r|
    ((days_mask || 0) & 2**DAYS.index(r)).zero?
  end
end