graphql

• Introduction
• API Documentation

Installation

Install from RubyGems by adding it to your Gemfile, then bundling.

# Gemfile
gem 'graphql'

$ bundle install

Overview

Declare types & build a schema

# Declare a type...
PostType = GraphQL::ObjectType.define do
  name "Post"
  description "A blog post"

  field :id, !types.ID
  field :title, !types.String
  field :body, !types.String
  field :comments, types[!CommentType]
end

# ...and a query root
QueryType = GraphQL::ObjectType.define do
  name "Query"
  description "The query root of this schema"

  field :post do
    type PostType
    argument :id, !types.ID
    resolve -> (obj, args, ctx) { Post.find(args["id"]) }
  end
end

# Then create your schema
Schema = GraphQL::Schema.new(query: QueryType)

See also:

• the test schema
• graphql-ruby-demo for an example schema on Rails

Execute queries

Execute GraphQL queries on a given schema, from a query string.

query = GraphQL::Query.new(Schema, query_string)
result_hash = query.result
# {
#   "data" => {
#     "post" => {
#        "id" => 1,
#        "title" => "GraphQL is nice"
#     }
#   }
# }

See also:

• query_spec.rb for an example of query execution.
• queries_controller.rb for a Rails example
• Try it on heroku

Use with Relay

If you're building a backend for Relay, you'll need:

• A JSON dump of the schema, which you can get by sending GraphQL::Introspection::INTROSPECTION_QUERY
• Relay-specific helpers for GraphQL like Connections, node fields, and global ids. Here's one example of those: graphql-relay

To Do

• Field merging
  • if you were to request a field, then request it in a fragment, it would get looked up twice
  • graphql/graphql-js#19 (comment)
• Code clean-up
  • Raise if you try to configure an attribute which doesn't suit the type
    • ie, if you try to define resolve on an ObjectType, it should somehow raise
• Big ideas:
  • Write Ruby bindings for libgraphqlparser and use that instead of Parslet
  • Add instrumentation
    • Some way to expose what queries are run, what types & fields are accessed, how long things are taking, etc

Goals

• Implement the GraphQL spec & support a Relay front end
• Provide idiomatic, plain-Ruby API with similarities to reference implementation where possible
• Support Ruby on Rails and Relay

Getting Involved

• Say hi & ask questions in the #ruby channel on Slack or on Twitter!
• Report bugs by posting a description, full stack trace, and all relevant code in a GitHub issue.
• Features & patches are welcome! Consider discussing it in an issue or in the #ruby channel on Slack to make sure we're on the same page.
• Run the tests with rake test or start up guard with bundle exec guard.

Other Resources

• GraphQL Spec
• Other implementations: graphql-links
• graphql-ruby + Rails demo (src / heroku)
• GraphQL Slack
• Example Relay support in Ruby
• graphql-parallel, an asynchronous query execution strategy

P.S.

• Thanks to @sgwilym for the great logo!
• Definition API heavily inspired by @seanchas's implementation of GraphQL