GraphQL Remote Loader

Performant, batched GraphQL queries from within the resolvers of a graphql-ruby API.

Snippet

For default error handling(null if errors) and no post-processing:

field :login, String, null: true, description: "The currently authenticated GitHub user's login."

def login
  GitHubLoader.load_value("viewer", "login")
end

If you need error handling, post-processing, or complex queries:

field :login, String, null: false, description: "The currently authenticated GitHub user's login."

def login
  GitHubLoader.load("viewer { login }").then do |results|
    if results["errors"].present?
      ""
    else
      results["data"]["viewer"]["login"].upcase
    end
  end
end

Full example

To see a working example of how graphql-remote_loader works, see the complete, working example application.

Description

graphql-remote_loader allows for querying GraphQL APIs from within resolvers of a graphql-ruby API.

This can be used to create GraphQL APIs that depend on data from other GraphQL APIs, either remote or local.

A promise-based resolution strategy from Shopify's graphql-batch is used to batch all requested data into a single GraphQL query. Promises are fulfilled with only the data they requested.

You can think of it as a lightweight version of schema-stitching.

How to use

First, you'll need to install the gem. Either do gem install graphql-remote_loader or add this to your Gemfile:

gem "graphql-remote_loader"

The gem provides a base loader GraphQL::RemoteLoader::Loader which does most of the heavy lifting. In order to remain client-agnostic, there's an unimplemented no-op that queries the external GraphQL API.

To use, create a new class that inherits from GraphQL::RemoteLoader::Loader and define def query(query_string). The method takes a query String as input. The expected output is a response Hash, or some object that responds to #to_h.

Example:

require "graphql/remote_loader"

module MyApp
  class GitHubLoader < GraphQL::RemoteLoader::Loader
    def query(query_string)
      parsed_query = GraphQLClient.parse(query_string)
      GraphQLClient.query(parsed_query)
    end
  end
end

This example uses graphql-client. Any client, or even just plain cURL/HTTP can be used.

With your loader setup, you can begin using #load or #load_value in your graphql-ruby resolvers.

Running tests

bundle install
bundle exec rspec