GraphQL::Preload

Provides a DSL for the graphql gem that allows ActiveRecord associations to be preloaded in field definitions. Based on a gist by @theorygeek.

This fork works with Ruby on Rails 6.0 and GraphQL-Ruby 1.10 (but not in interpreter mode yet).

Installation

Add this line to your application's Gemfile:

gem 'graphql-preload'

And then execute:

$ bundle

Or install it yourself as:

$ gem install graphql-preload

Usage

First, enable preloading in your GraphQL::Schema:

class PreloadSchema < GraphQL::Schema
  use GraphQL::Batch

  enable_preloading

  query QueryType
end

Call preload when defining your field:

class PostType < GraphQL::Schema::Object
  # This runs Post.includes(:comments) but only if comments are requested
  field :comments,  [CommentType], null: false, preload: :comments

  # Block syntax is supported too
  field :comments,  [CommentType], null: false
    preload :comments

    # Post.includes(:comments, :authors)
    preload [:comments, :authors]

    # Post.includes(:comments, authors: [:followers, :posts])
    preload [:comments, { authors: [:followers, :posts] }]
  end
end

preload_scope

Starting with Rails 4.1, you can scope your preloaded records by passing a valid scope to ActiveRecord::Associations::Preloader. Scoping can improve performance by reducing the number of models to be instantiated and can help with certain business goals (e.g., only returning records that have not been soft deleted).

This functionality is surfaced through the preload_scope option:

class UserType < GraphQL::Schema::Object
  field :posts, [PostType], null: false,
                            preload: :posts,
                            preload_scope: ->(*) { Post.order(rating: :desc) }
end

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake test 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.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/ConsultingMD/graphql-preload.

License

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