active record quering in rails 4 and postgres - ruby-on-rails

Question

I have 2 models
Class Ride
has_many :trips
#state (string: active or expired)
end
Class Trip
#date (Date attribute)
scope :active, -> (start_at = Date.today) { where("trips.date >= ?", [Date.today, start_at].max) }
end
Daily, I need update state on Rides with active state having all trips with date attribute < Date.today
how to perform this in 1 query?
i can archive such result using:
Ride.with_active_state.select{|r| r.trips.active.size ==0}
but it makes huje queries to count trips, eq:
[1] pry(main)> Ride.with_active_state.select{|r| r.trips.active.size ==0}
(7.3ms) SELECT f_geometry_column,coord_dimension,srid,type FROM geometry_columns WHERE f_table_name='rides'
Ride Load (1.6ms) SELECT "rides".* FROM "rides" WHERE (rides.workflow_state = 'active')
(2.9ms) SELECT f_geometry_column,coord_dimension,srid,type FROM geometry_columns WHERE f_table_name='trips'
(1.3ms) SELECT COUNT(*) FROM "trips" WHERE "trips"."ride_id" = $1 AND (trips.date >= '2013-09-24') [["ride_id", 9]]
(0.7ms) SELECT COUNT(*) FROM "trips" WHERE "trips"."ride_id" = $1 AND (trips.date >= '2013-09-24') [["ride_id", 10]]
(0.7ms) SELECT COUNT(*) FROM "trips" WHERE "trips"."ride_id" = $1 AND (trips.date >= '2013-09-24') [["ride_id", 11]]
(0.7ms) SELECT COUNT(*) FROM "trips" WHERE "trips"."ride_id" = $1 AND (trips.date >= '2013-09-24') [["ride_id", 12]]
(0.8ms) SELECT COUNT(*) FROM "trips" WHERE "trips"."ride_id" = $1 AND (trips.date >= '2013-09-24') [["ride_id", 13]]
(0.8ms) SELECT COUNT(*) FROM "trips" WHERE "trips"."ride_id" = $1 AND (trips.date >= '2013-09-24') [["ride_id", 14]]
(0.5ms) SELECT COUNT(*) FROM "trips" WHERE "trips"."ride_id" = $1 AND (trips.date >= '2013-09-24') [["ride_id", 15]]
(0.5ms) SELECT COUNT(*) FROM "trips" WHERE "trips"."ride_id" = $1 AND (trips.date >= '2013-09-24') [["ride_id", 16]]
(0.5ms) SELECT COUNT(*) FROM "trips" WHERE "trips"."ride_id" = $1 AND (trips.date >= '2013-09-24') [["ride_id", 17]]
(0.5ms) SELECT COUNT(*) FROM "trips" WHERE "trips"."ride_id" = $1 AND (trips.date >= '2013-09-24') [["ride_id", 18]]
(0.5ms) SELECT COUNT(*) FROM "trips" WHERE "trips"."ride_id" = $1 AND (trips.date >= '2013-09-24') [["ride_id", 19]]
(0.5ms) SELECT COUNT(*) FROM "trips" WHERE "trips"."ride_id" = $1 AND (trips.date >= '2013-09-24') [["ride_id", 20]]
....

Answer 1

Add scopes on Ride with a group and having clause. It would check the count of all future trips of a ride and return the rides with 0 count.
Class Ride
scope :active_state, where(state: "active")
scope :with_nonactive_trips, -> (start_date = Date.today){ joins(:trips).
group("rides.id").
having( ["sum(trips.date > ?) = 0",start_date] ) }
end
Ride.active_state.with_nonactive_trips
# returns All the rides with state == active, alteast one trip and having no trips with date > Date.today
Using a lambda since you had it on the active scope in Trip. I am guessing you need to use a different date than Date.today for some queries.