GraphQL Client by GitHub is a Ruby library for declaring, composing and executing GraphQL queries.

Installation

Add graphql-client to your Gemfile and then run bundle install.

# Gemfile
gem 'graphql-client'

Configuration

Sample configuration for a GraphQL Client to query from the SWAPI GraphQL Wrapper.

Tip:

Always remember to replace API_SECRET in the Bearer Token and project-id in the URL with the correct values from the Apito console.
If you are unsure where to find your API secrets and endpoints for your project, visit this page.

require "graphql/client"
require "graphql/client/http"

# Star Wars API example wrapper
module SWAPI
  # Configure GraphQL endpoint using the basic HTTP network adapter.
  HTTP = GraphQL::Client::HTTP.new("https://api.apito.io/secured/graphql") do
    def headers(context)
      # Must Set the Authorization Headers
      { "Authorization": "Bearer API_SECRET" }
    end
  end

  # Fetch latest schema on init, this will make a network request
  Schema = GraphQL::Client.load_schema(HTTP)

  # However, it's smart to dump this to a JSON file and load from disk
  #
  # Run it from a script or rake task
  #   GraphQL::Client.dump_schema(SWAPI::HTTP, "path/to/schema.json")
  #
  # Schema = GraphQL::Client.load_schema("path/to/schema.json")

  Client = GraphQL::Client.new(schema: Schema, execute: HTTP)
end

Defining Queries

If you haven’t already, familiarize yourself with the GraphQL query syntax. Queries are declared with the same syntax inside of a <<-'GRAPHQL' heredoc. There isn’t any special query builder Ruby DSL.

This client library encourages all GraphQL queries to be declared statically and assigned to a Ruby constant.

HeroNameQuery = SWAPI::Client.parse <<-'GRAPHQL'
  query {
    hero {
      name
    }
  }
GRAPHQL

Queries can reference variables that are passed in at query execution time.

HeroFromEpisodeQuery = SWAPI::Client.parse <<-'GRAPHQL'
  query($episode: Episode) {
    hero(episode: $episode) {
      name
    }
  }
GRAPHQL

Fragments are declared similarly.

HumanFragment = SWAPI::Client.parse <<-'GRAPHQL'
  fragment on Human {
    name
    homePlanet
  }
GRAPHQL

To include a fragment in a query, reference the fragment by constant.

HeroNameQuery = SWAPI::Client.parse <<-'GRAPHQL'
  {
    luke: human(id: "1000") {
      ...HumanFragment
    }
    leia: human(id: "1003") {
      ...HumanFragment
    }
  }
GRAPHQL

This works for namespaced constants.

module Hero
  Query = SWAPI::Client.parse <<-'GRAPHQL'
    {
      luke: human(id: "1000") {
        ...Human::Fragment
      }
      leia: human(id: "1003") {
        ...Human::Fragment
      }
    }
  GRAPHQL
end

:: is invalid in regular GraphQL syntax, but #parse makes an initial pass on the query string and resolves all the fragment spreads with constantize.

Executing queries

Pass the reference of a parsed query definition to GraphQL::Client#query. Data is returned back in a wrapped GraphQL::Client::Schema::ObjectType struct that provides Ruby-ish accessors.

result = SWAPI::Client.query(Hero::Query)

# The raw data is Hash of JSON values
# result["data"]["luke"]["homePlanet"]

# The wrapped result allows to you access data with Ruby methods
result.data.luke.home_planet

GraphQL::Client#query also accepts variables and context parameters that can be leveraged by the underlying network executor.

result = SWAPI::Client.query(Hero::HeroFromEpisodeQuery, variables: {episode: "JEDI"}, context: {user_id: current_user_id})

Detailed Guide

For a detailed guide, be sure to check out the official github page here