gem "kumolus-mongoid-enum"

class Payment
  include Mongoid::Document
  include Mongoid::Enum

  enum :status, [:pending, :approved, :declined]
end

payment = Payment.create

payment.status
# => :pending

payment.approved!
# => :approved

payment.pending?
# => :false

Payment.approved
# => Mongoid::Criteria for payments with status == :approved