How To Set Up a Ruby on Rails GraphQL API

Total Blog Views: 44

Blog Status: publish

Created By: charlie Created at: 08-07-2021

Tags: ruby on rails graphql api restapis

Hi there!
Let’s integrate GraphQL in your Rails application and create your first
GraphQL query.
Must have installed in your system:

Ruby
Rails
PostgreSQL

STEP 1: Creating new Rails Application:

To create a new API only Rails application with PostgreSQL
database run:

rails new rails_graphql_demo -d postgresql -T --api

Once application is created, goto :

cd rails_graphql_demo

Run below command to create database :

rails db:create

Output
Created database 'rails_graphql_development'
Created database 'rails_graphql_test'

First step is completed, let’s verify if you did it correctly:

Start the Rails application: rails s
Visit: http://localhost:3000

Note:This file should have auto generated sample query code:

module Types

class QueryType < Types::BaseObject

field :test_field, String, null: false,

description: "An example field added by the generator"

def test_field

"Hello World!"

end

And #config/routes.rb

Rails.application.routes.draw do
post "/graphql", to: "graphql#execute"
# For details on the DSL available within this file, see https://guides.rubyonrails.org/routing.html
end

Start the application and install your preferable GraphQL IDE/tool
and check the test_field query

BONUS STEP: Creating User List query:

Create User model and add few columns:

rails g model User first_name last_name email
rails db:migrate

Next, open db/seeds.rb and add:

n = 5
n.times do | i|
User.create(first_name: "demo#{i}", last_name: "user#{i}", email: "user#{i}@demo.com")
end
puts "Great..#{n} users added.."

Run Below Command

rails db:seed

And replace test_field with real users field:

field :users, [Types::UserType], null: false,
description: "Returns all users"
def users
User.all
end

Now define UserType

rails g graphql:object user

This will create file: app/graphql/types/user_type.rb

module Types
class UserType < Types::BaseObject
field :id, ID, null: false
field :first_name, String, null: true
field :last_name, String, null: true
field :email, String, null: true
field :created_at, GraphQL::Types::ISO8601DateTime, null: false
field :updated_at, GraphQL::Types::ISO8601DateTime, null: false
end
end

Let’s check this, how it looks: