Question

I’m wondering how to join up two different models, and then sort them by via another associated model.

Say I’ve got an ACCOUNT, that has_many CARS and BIKES, and they both have a polymorphic relation (has_one) to a WHEELSET.

How would I write a query to select all bikes and cars for a given account, and have them sorted by the wheelset (or another column in the wheelset model?)

Account
has_many :cars, :bikes

Bike
belongs_to :account
has_one wheelset, :as => wheelable

Car
belongs_to :account
has_one wheelset, :as => wheelable

Wheelset
belongs_to :wheelable, :polymorphic => true

I’m thinking something like the following, (which doesn’t work unfortunately)

a = Account.first
sets = a.bikes.includes(:wheelset) + self.cars.includes(:wheelset)
sets.order('wheelset.wheels ASC')

Answer 1

You could build an standard Ruby array and use the array sort method to order them.

a = Account.first
sets = Array.new
sets += a.bikes + a.cars
sets.sort! { |a, b| a.wheelable <==> b.wheelable }

I havent tested this but its roughly how I would go about it given this situation.