Getting Started

Installation

You can install graphql from RubyGems by adding to your application’s Gemfile:

# Gemfile gem "graphql" 

Then, running bundle install:

$ bundle install 

Getting Started

On Rails, you can get started with a few GraphQL generators:

# Add graphql-ruby boilerplate and mount graphiql in development $ rails g graphql:install # You may need to run bundle install again, as by default graphiql-rails is added on installation. $ bundle install # Make your first object type $ rails g graphql:object Post title:String rating:Int comments:[Comment] 

Or, you can build a GraphQL server by hand:

• Define some types
• Connect them to a schema
• Execute queries with your schema

Declare types

Types describe objects in your application and form the basis for GraphQL’s type system.

# app/graphql/types/post_type.rb module Types class PostType < Types::BaseObject description "A blog post" field :id, ID, null: false field :title, String, null: false # fields should be queried in camel-case (this will be `truncatedPreview`) field :truncated_preview, String, null: false # Fields can return lists of other objects: field :comments, [Types::CommentType], # And fields can have their own descriptions: description: "This post's comments, or null if this post has comments disabled." end end # app/graphql/types/comment_type.rb module Types class CommentType < Types::BaseObject field :id, ID, null: false field :post, PostType, null: false end end 

Build a Schema

Before building a schema, you have to define an entry point to your system, the “query root”:

class QueryType < GraphQL::Schema::Object description "The query root of this schema" field :post, resolver: Resolvers::PostResolver end 

Define how this field is resolved by creating a resolver class:

# app/graphql/resolvers/post_resolver.rb module Resolvers class PostResolver < BaseResolver type Types::PostType, null: false argument :id, ID def resolve(id:) ::Post.find(id) end end end 

Then, build a schema with QueryType as the query entry point:

class Schema < GraphQL::Schema query Types::QueryType end 

This schema is ready to serve GraphQL queries! Browse the guides to learn about other GraphQL Ruby features.

Execute queries

You can execute queries from a query string:

query_string = " { post(id: 1) { id title truncatedPreview } }" result_hash = Schema.execute(query_string) # { # "data" => { # "post" => { # "id" => 1, # "title" => "GraphQL is nice" # "truncatedPreview" => "GraphQL is..." # } # } # } 

See Executing Queries for more information about running queries on your schema.

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, see the Connection guide, Mutation guide, and Object Identification guide.

Use with Apollo Client

Apollo Client is a full featured, simple to use GraphQL client with convenient integrations for popular view layers. You don’t need to do anything special to connect Apollo Client to a graphql-ruby server.

Use with GraphQL.js Client

GraphQL.js Client is a tiny client that is platform- and framework-agnostic. It works well with graphql-ruby servers, since GraphQL requests are simple query strings transported over HTTP.