Question

I have two models: Car and Engine.
One Car must have one engine.

My model associations

class Car < ActiveRecord::Base
  belongs_to :engine

  attr_accessible :name, :engine_id              
end

and

class Engine < ActiveRecord::Base
  has_many :cars

  attr_accessible :name
end

I know how to show Engine data via Car:

Car.first.engine

This returns

irb(main):001:0> Car.first.engine
  ←[1m←[36mCar Load (0.0ms)←[0m  ←[1mSELECT "cars".* FROM "cars" LIMIT 1←[0m
  ←[1m←[35mEngine Load (0.0ms)←[0m  SELECT "engines".* FROM "engines" WHERE "engines"."id" = 1 LIMIT 1
=> #<Engine id: 1, name: "Benzine", created_at: "2012-11-27 12:09:08", updated_at: "2012-11-27 12:09:08">

But how to show car and engine together?

Sample:
car_id: 1, car_name: Audi, engine_name: Benzine

Answer 1

Car.joins(:engine).includes(:engine).select("cars.name, engines.name")