GraphqlPreloadQueries

This gem permits your graphql application to define association preloads to improve app performance by removing N+1 query issues.

• Object Type

  class UserType < Types::BaseObject
    field :id, Int, null: true
    field :name, String, null: true
    field :parents, [Types::UserType], null: false, preload: true
    field :friends, [Types::UserType], null: false, preload: :user_friends
  end

  preload: accepts:

  • true: Will use field key as the association name
    field :parents, ..., preload: true will preload parents association
  • Symbol: Custom association name
    field :friends, ..., preload: :user_friends will preload user_friends association
  • String: Tied associations
    field :excluded_friends, ..., preload: 'excluded_friends.user' will preload excluded_friends -> user association
  • Hash: Deep preload definitions
    field :best_friends, ..., preload: { preload: :user_friends, parents: :parents }'
    • Will preload user_friends and user_friends.parents only if query includes inner definition, like user(id: 10) { bestFriends { id parents { ... } } }
    • Will not preload user_friends.parents if query does not include inner definition, like user(id: 10) { bestFriends { id } }

• Preloads in query results

  • BEFORE

      # queries/users.rb
      def users(ids:)
        users = User.where(id: ids)
      end

    Does not apply preloads to the root query.

  • AFTER

      def users(ids:)
        users = User.where(id: ids)
        users = include_gql_preloads(users)
      end

    Root query applies all defined preloads

  • include_gql_preloads(collection, query_key: nil, type_klass: nil): Will include all preloads configured in type_klass (UserType) based on the gql query.

    • collection (ActiveRecordCollection) Query results
    • query_key (String | Sym, default: method name) Field result key
    • type_klass: (GQL TypeClass, default: calculates using query_key)

• Preloads in mutation results

    # mutations/users/disable.rb
    #...
    field :users, [Types::UserType], null: true  
    def resolve(ids:)
      affected_users = User.where(id: ids)
      affected_users = include_gql_preloads(affected_users, query_key: :users)
      { users: affected_users }
    end

  • include_gql_preloads(collection, query_key: , type_klass: nil): Will include all preloads configured in type_klass (UserType) based on the gql query.
    • collection (ActiveRecordCollection) Query results
    • query_key (String | Sym) Field result key
    • type_klass: (GQL TypeClass, default: calculates using query_key)

Add this line to your application's Gemfile:

gem 'graphql_preload_queries'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install graphql_preload_queries

For debugging mode:

  # config/initializers/gql_preload.rb
  GraphqlPreloadQueries::DEBUG = true

Bug reports and pull requests are welcome on GitHub at https://github.com/owen2345/graphql_preload_queries. 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.