Create REST API with Ruby On Rails (Part 1)

What Is REST?

Read this post https://www.codecademy.com/article/what-is-rest

Init Rails API Only Project

rails new ideas-api --api --database=postgresql

Handle Cross-Origin Resource Sharing (CORS)

Rails use rack-cors to avoid CORS issues when API is called from the frontend app (Read more: https://github.com/cyu/rack-cors).

Add the following line to Gemfile, then run bundle install:

gem 'rack-cors'

Insert rack CORS middleware to rails app. Create a file config/initializers/cors.rb with following content:

Create Idea Resource

Generate Idea model with these attributes: id, title, description, created_at, updated_at.

rails g model Idea title:string description:text
rails db:migrate

Add validations for Idea model, modify file app/models/idea.rb with following content:

Let's add some sample data, modify file db/seed.rb with below code then run rails db:seed (Note: I use faker gem to generate dummy text):

Build Idea APIs

Config api routes, modify file config/routes.rb with following code:

Define Idea controller, create files app/controllers/api/v1/base_controller.rb , app/controllers/api/v1/ideas_controller.rb with following code:

After this step, it's done for super basic REST API, you can boot up your server rails s and start to test your apis (I suggest to use Postman app).

Using JSONAPI Serializer To Render JSON

Sometimes you want more control in what be in JSON response. This might be required for:

• Adding some custom (virtual) attributes to resource
• Generating relationships between resources
• Having standard formats like JSONAPI

It’s time for jsonapi-serializer, jsonapi.rb gems.

Add the following line to Gemfile, then run bundle install:

gem 'jsonapi-serializer'
gem 'jsonapi.rb'

Install jsonapi.rb for rails app, create a file config/initializers/jsonapi.rb with following lines:

Define IdealSerializer by creating new files app/serializers/base_serializer.rb, app/serializers/idea_serializer.rb with following code:

To apply serializer to json response, modify file app/controllers/api/v1/ideas_controller.rb like below:

Paginate Resource List Whenever You Can

I strongly recommend you use pagy gem to handle pagination. It has great performance, you can visit https://github.com/ddnexus/pagy to see performance comparison with other gems.

Add the following line to Gemfile, then run bundle install:

gem 'pagy'

Config your pagy, create a file config/initializers/pagy.rb with following code:

Include Pagy::Backend to Api::V1::BaseController and add page_number, page_size methods to get pagination params.

Modify index method in app/controllers/api/v1/ideas_controller.rb:

Restart rails server and test your apis again.

You can clone final source code of part 1 from here https://gitlab.com/tranquangvu/ideas-api/-/tree/part-1

Done!