How do we add the Active Model Serializer to Ruby on Rails?

Create a new Rails API application named “simple-rest-api” using the rails new command.

rails new simple-rest-api --api
cd simple-rest-api

Generate the User, Book, and Subject models using the rails generate model command.

rails generate model User username:string password:string
rails generate model Book user:references book:string likes_books:integer
rails generate model Subject book:references subject:string likes_subjects:integer

Set up associations between the models by defining the relationships in the corresponding model files (app/models/user.rb, app/models/book.rb, and app/models/subject.rb).

Run the database migrations to create the necessary tables.

rails db:migrate

Generate controllers for the API endpoints using the rails g controller command.

rails g controller api/v1/Users
rails g controller api/v1/Books
rails g controller api/v1/Subjects

Define the routes for the API endpoints in the routes.rb file, specifying the nested resource structure.

namespace :api do
  namespace :v1 do
    resources :users do
      resources :books
      resources :subjects
    end
  end
end

Add the active_model_serializers gem to the Gemfile and run bundle install.

gem 'active_model_serializers'
bundle install

Generate a serializer for the User model using the rails g serializer command.

rails g serializer user

Add the seed data to populate the database with dummy user records.

user = (1..50).map do
  User.create!(
    username: "user",
    password: "123456"
  )
end

Run the seed task to insert the data into the database.

rails db:seed

Implement the index action in the UsersController to fetch all users and render the response in JSON format using the Active Model Serializers gem.

def index
  @users = User.all
  render json: {
    data: ActiveModelSerializers::SerializableResource.new(@users, each_serializer: UserSerializer),
    message: ['Employee list fetched successfully'],
    status: 200,
    type: 'Success'
  }
end

This setup allows you to build a simple REST API for managing users, books, and subjects with their respective associations. The code provided demonstrates the basic structure and functionality, but you can expand on it to add more actions, validations, and error handling as per your requirements.

Run rails s and browser hit this URL http://localhost:3000/api/v1/users

We are getting below output

{"data":[{"id":1,"username":"bhartee","password":"123456"},{"id":2,"username":"user","password":"123456"},{"id":3,"username":"user","password":"123456"},{"id":4,"username":"user","password":"123456"},{"id":5,"username":"user","password":"123456"},{"id":6,"username":"user","password":"123456"},{"id":7,"username":"user","password":"123456"},{"id":8,"username":"user","password":"123456"},{"id":9,"username":"user","password":"123456"},{"id":10,"username":"user","password":"123456"},{"id":11,"username":"user","password":"123456"},{"id":12,"username":"user","password":"123456"},{"id":13,"username":"user","password":"123456"},{"id":14,"username":"user","password":"123456"},{"id":15,"username":"user","password":"123456"},{"id":16,"username":"user","password":"123456"},{"id":17,"username":"user","password":"123456"},{"id":18,"username":"user","password":"123456"},{"id":19,"username":"user","password":"123456"},{"id":20,"username":"user","password":"123456"},{"id":21,"username":"user","password":"123456"},{"id":22,"username":"user","password":"123456"},{"id":23,"username":"user","password":"123456"},{"id":24,"username":"user","password":"123456"},{"id":25,"username":"user","password":"123456"},{"id":26,"username":"user","password":"123456"},{"id":27,"username":"user","password":"123456"},{"id":28,"username":"user","password":"123456"},{"id":29,"username":"user","password":"123456"},{"id":30,"username":"user","password":"123456"},{"id":31,"username":"user","password":"123456"},{"id":32,"username":"user","password":"123456"},{"id":33,"username":"user","password":"123456"},{"id":34,"username":"user","password":"123456"},{"id":35,"username":"user","password":"123456"},{"id":36,"username":"user","password":"123456"},{"id":37,"username":"user","password":"123456"},{"id":38,"username":"user","password":"123456"},{"id":39,"username":"user","password":"123456"},{"id":40,"username":"user","password":"123456"},{"id":41,"username":"user","password":"123456"},{"id":42,"username":"user","password":"123456"},{"id":43,"username":"user","password":"123456"},{"id":44,"username":"user","password":"123456"},{"id":45,"username":"user","password":"123456"},{"id":46,"username":"user","password":"123456"},{"id":47,"username":"user","password":"123456"},{"id":48,"username":"user","password":"123456"},{"id":49,"username":"user","password":"123456"},{"id":50,"username":"user","password":"123456"},{"id":51,"username":"user","password":"123456"}],"message":["Employee list fetched successfully"],"status":200,"type":"Success"}