gem 'graphql_rails'

# config/graphql/routes.rb
GraphqlRails::Router.draw do
  # will create createUser, updateUser, destroyUser mutations and user, users queries.
  # expects that UsersController class exist
  resources :users

  # if you want custom queries or mutation
  query 'searchLogs', to: 'logs#search' # action is handled by LogsController#search
end

# app/models/user.rb
class User # works with any class including ActiveRecord
  include GraphqlRails::Model

  graphql do |c|
    # most common attributes, like :id, :name, :title has default type, so you don't have to specify it (but you can!)
    c.attribute(:id)

    c.attribute(:email).type('String')
    c.attribute(:surname).type('String')
  end
end

# app/controllers/graphql/users_controller.rb
class Graphql::UsersController < GraphqlApplicationController
  model('User') # specify that all actions returns User by default

  # DRUD actions description
  action(:index).permit(id: 'ID!').returns_many
  action(:show).permit(id: 'ID!').returns_single
  action(:create).permit(email: 'String!').returns_single
  action(:update).permit(id: 'ID!', email: 'String!').returns_single
  action(:destroy).permit(id: 'ID!').returns_single

  def index
    User.all
  end

  def show
    User.find(params[:id])
  end
  # ... code for create / update / destroy is skipped ...
end

# spec/spec_helper.rb
require 'graphql_rails/rspec_controller_helpers'

RSpec.configure do |config|
  config.include(GraphqlRails::RSpecControllerHelpers, type: :graphql_controller)
  # ... your other configuration ...
end

class MyGraphqlController
  action(:create_user).permit(:full_name, :email).returns(User)
  action(:index).returns('String')

  def index
    "Called from index: #{params[:message]}"
  end

  def create_user
    User.create!(params)
  end
end

RSpec.describe MyGraphqlController, type: :graphql_controller do
  describe '#index' do
    it 'is successful' do
      query(:index)
      expect(response).to be_successful
    end

    it 'returns correct message' do
      query(:index, params: { message: 'Hello world!' })
      expect(response.result).to eq "Called from index: Hello world!"
    end
  end

  describe '#create_user' do
    context 'when bad email is given' do
      it 'fails' do
        mutation(:create_user, params { email: 'bad' })
        expect(response).to be_failure
      end

      it 'contains errors' do
        mutation(:create_user, params { email: 'bad' })
        expect(response.errors).not_to be_empty
      end
    end
  end
end

# config/initializers/graphql_rails.rb
GraphqlRails::Integrations.enable(:lograge, :sentry)