How to preload Rails scopes

Rails’ scopes make it easy to find the records you want:

app/models/review.rb1 2 3 4 5 class Review < ActiveRecord::Base belongs_to :restaurant scope :positive, - { where("rating 3.0") } end 1 2 3 4 irb(main):001:0 Restaurant.first.reviews.positive.count Restaurant Load (0.4ms) SELECT `restaurants`.* FROM `restaurants` ORDER BY `restaurants`.`id` ASC LIMIT 1 (0.6ms) SELECT COUNT(*) FROM `reviews` WHERE `reviews`.`restaurant_id` = 1 AND (rating 3.0) = 5

But if you’re not careful with t...

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