gistfile1.txt

  one_through_one :accepted_car_request_transition,
                  class: CarRequestTransition,
                  join_table: :car_requests,
                  right_key: :id,
                  right_primary_key: :car_request_id,
                  left_key: :car_request_group_id,
                  left_primary_key: :id,
                  conditions: {
                    accepted_car_request_transition__most_recent: true,
                    accepted_car_request_transition__to_state: 'accepted'
                  }