Activerecord::PreloadQuery

PreloadQuery allows you to preload queries and have them available as the relations when use the preload method of ActiveRecord.

For example, given Category and Product classes and a method that adds the products' prices in a category, like self.sum_price:

class Category < ActiveRecord::Base
  has_many :products

  class << self
    def sum_price(ids)
      where(id: ids).group("categories.id").joins(:products).select("categories.id, sum(products.price) AS sum_price")
    end
  end
end

class Product < ActiveRecord::Base
  belongs_to :category
end

we can write:

Category.limit(10).preload_query(:sum_price).each do |category|
  p category.name
  p category.sum_price
end

The method to be preloaded must return an enumerable. Each element must respond to the primary_key of the class and the same method name.

Add this line to your application's Gemfile:

gem 'activerecord-preload_query'

And then execute:

$ bundle

Or install it yourself as:

$ gem install activerecord-preload_query

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/ceritium/activerecord-preload_query. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

The gem is available as open source under the terms of the MIT License.