A base 36 incrementing Counter Model for Mongoid

Counter.rb

module CounterIncrementor
  def next(counter_name)
    counter = self.find_by(name: counter_name)
    counter.increment
  end
end

class Counter
  include Mongoid::Document
  include Mongoid::Timestamps
  extend CounterIncrementor

  field :name, type: String
  field :sequence_value, type: String, default: '0000000000'

  def increment
    set(sequence_value: self.inc_lamba.call(self.sequence_value), updated_at: Time.now)
  end

  def inc_lamba
    ->s{(s.to_i(36)+1).to_s(36).rjust 10,?0}
  end

end