Enums in Rails without ActiveRecord

Question

I want to use enums with MongoMapper and rails 4. I know there are gems out there (enumerize) which adds this behaviour but it seems like a lot to add for a small feature.

What is the easiest way of creating an enum for an ActiveModel class?

Answer 1

Using getters, setters and an array of constants this can be quickly achieved:

class Subscription
  include MongoMapper::Document
  ...

  key :status, Integer

  STATE = [:queued, :submitted, :processing, :payment_received, :fully_paid, :error]

  def status=(str)
    @status = STATE.index(str)
  end

  def status
    STATE[@status]
  end
end

You could even add checks for common queries, eg the error state may need to be checked more often than others and you can skip the symbol > integer conversion:

def errors?
  @status == 5
end