fooo.rb

class Invite
  add_state :accepted, :after => :accept_job

  add_event(:accept) do
    transitions :to => :accepted, :from => :pending
  end

  private
  def accept_job
    unless job.accept!
      raise "Unable to accept job"
    end
  end

end

# Usage code:

Invite.transaction do
  invite.accept!
end