How to make REST API in Rails | Part 2

How to make REST API in Rails

Making a simple API in rails 

We have seen in the part-1 of this post "How to make an end point through ReST to get the user info as Json". If you haven't covered up part-1, please go through it to have a better understanding of this tutorial.

So far, we have created an end point for show action which look like:

http://localhost:3000/api/v1/users/1

Now we will make more endpoints to create, update and delete a user.

Create action in Rails API

Let's code "create" action in app/controllers/api/v1/users_controller.rb

class Api::V1::UsersController < ApplicationController
  respond_to :json
  skip_before_filter  :verify_authenticity_token

  def show
    respond_with User.find(params[:id])
  end

  def create
   user=User.new(user_params) 

        # if the user is saved successfully than respond with json data and status code 201

        if user.save 
    render json: user, status: 201
   else
    render json: { errors: user.errors}, status: 422
   end
  end

  private
  def user_params
   params.require(:user).permit(:email, :password, :password_confirmation) 

        end

end 

Here we have another private method user_params to sanitize the attributes to be assigned through mass-assignment. After successful creation of the user we are responding with the json data and status code 201.

Now, we need to tell our config/routes.rb file that we also have create action. Let's add create action in config/routes.rb file

Rails.application.routes.draw do

  # API routes path
  namespace :api, defaults: { format: :json } do
    namespace :v1 do
      #devise_for :users
      resources :users, :only => [:show, :create]
    end
  end  
end

Hurray!!! We have successfully created the endpoint to create a user  which you can check through by sending a post request through POSTMAN (A tool to check API endpoints).

POST request through postman to create a user

Response of the POST request

Update action in Rails API

Time to update the user being already created. The update action responds to PUT/PATCH request.

Let's add update action to app/controllers/api/v1/users_controller.rb

class Api::V1::UsersController < ApplicationController
  respond_to :json
  skip_before_filter  :verify_authenticity_token

  def show
    respond_with User.find(params[:id])
  end

  # Creating users
  def create
    user=User.new(user_params)

    if user.save 
      render json: user, status: 201 
    else
      render json: { errors: user.errors}, status: 422
    end
  end

  # Updating users
  def update
    user = User.find(params[:id])

    if user.update(user_params)
      render json: user, status: 200
    else
      render json: { errors: user.errors }, status: 422
    end
  end

  private

  def user_params
   params.require(:user).permit(:email, :password, :password_confirmation)
  end
end

You might have guessed the next step, yes, now we need to add the update action in config/routes.rb file too. So let's do it.

Rails.application.routes.draw do

  # API routes path
  namespace :api, defaults: { format: :json } do
    namespace :v1 do
      #devise_for :users
      resources :users, :only => [:show, :create, :update]
    end
  end  
end

Now Let's test our update action.

Update action through POSTMAN 

Update action response

Destroy action in Rails API

Destroy action is used to delete a record and here we are going to delete a user. So let's add the destroy action in app/controllers/api/v1/users_controller.rb

class Api::V1::UsersController < ApplicationController
  respond_to :json
  skip_before_filter  :verify_authenticity_token

  def show
    respond_with User.find(params[:id])
  end

  # Creating users
  def create
    user=User.new(user_params)

    if user.save 
      render json: user, status: 201 
    else
      render json: { errors: user.errors}, status: 422
    end
  end

  # Updating users
  def update
    user = User.find(params[:id])

    if user.update(user_params)
      render json: user, status: 200
    else
      render json: { errors: user.errors }, status: 422
    end
  end

  # Deleting users
  def destroy
    user = User.find(params[:id])
    user.destroy
    head 204
  end

  private

  def user_params
   params.require(:user).permit(:email, :password, :password_confirmation)
  end
end

Here we are deleting the user with a particular ID which is being passed as a parameter and after successful deletion of the user we are giving 204 code which means the server has processed the request and doesn't return any content. We may also respond with 200 status code but this is more suitable.

Remember to update config/routes.rb file

Rails.application.routes.draw do

  # API routes path
  namespace :api, defaults: { format: :json } do
    namespace :v1 do
      #devise_for :users
      resources :users, :only => [:show, :create, :update, :destroy]
    end
  end  
end

Destroy action with POSTMAN

Destroy action response

Congratulations!! you are done with the CRUD part of a ReSTful API in Rails.

Further you can dockerize this Rails app - Follow this post to dockerize this API