Question

I`m having a problem with search query in Rails 3 application using Mongoid. My models are:

class Offer
  has_many :waypoints
end

class Waypoint
  belongs_to :offer
  field: address
  field: order, type: Integer
end

So each Offer has several Waypoints and these Waypoints has order. Waypoint with the smallest order is start point, with the biggest – destination point.

Task: We have “To” and “From” addresses. We need to find all the offers, which waypoints contain these addresses in proper order.

Problem: I can`t find useful query for it. In mongoid documentation I found smth like

Offer.where(“waypoints.address” => “Berlin”) but it works only if Waypoints were embedded.

Which solutions for such a problem do you know?

P.S.
So I probably will create another table WaypointsCache with field like (for each offer there will be several caches with different from-to combos):

class WaypointCache
  field: from
  field: to
  field: offer_id
end

Answer 1

If the goal is to find all Offers with a waypoint address of Berlin, then you have a couple of options.

1. Move the waypoints to be embedded inside of the offer.
2. execute two queries, like so:

Code:

waypoints = Waypoint.where(:address => "Berlin").only(:offer_id).all
offer_ids = waypoints.map(&:offer_id)
offers = Offer.any_in(:_id => offer_ids).all