EagerCounting

Avoid N+1 Queries caused by count calls!

Add this line to your application's Gemfile:

gem 'eager_counting', '~> 0.1'

And then execute:

$ bundle

Or install it yourself as:

$ gem install eager_counting

Include the EagerCounting::CountBy module on any ActiveRecord class.

class Comment < ActiveRecord::Base
  include EagerCounting::CountBy
  belongs_to :author
  belongs_to :commentable, polymorphic: true
end

This will allow you to call count_by on scopes of this class. count_by performs a count grouped by the given association. This means it will return a hash mapping the ids of the associated objects to the number of rows this class has for each of them.

Comment.count_by(:author) # => hash with author id mapped to number of comments this user made

You can call this method on any relation object of the class you included it on

Comment.where(spam: false).count_by(:author) # => will only count non spam comments

With the second argument you can also limit the scope of the association by which to count

Comment.count_by(:author, User.where(admin: false)) # => only count comments by non admin users

By passing an hash as the association you can count by joined associations

Comment.count_by(author: { city: :country }) # => count comments by the country their from

You can also use it on polymoprhic associations. For that the second parameter is necessary to select the type of things to count by.

Comment.count_by(:commentable, Picture.all) # => how many comments does each picture have?

After checking out the repo, run bin/setup to install dependencies. 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/[USERNAME]/foobar. 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.