Serving Your Personal Tutor with a RESTful API Using Sinatra

Welcome to the next step in our journey of building a personal tutor service with Sinatra, a lightweight Ruby web framework. In the previous lesson, we focused on the TutorController, which manages tutoring sessions and handles student queries by interacting with both the model and service layers. Now, we will take a significant step forward by creating a RESTful API for our personal tutor service using Sinatra . We'll start by setting up the main Sinatra application, then adapt the TutorController to integrate with Sinatra's session management.

Understanding RESTful APIs and Sinatra

RESTful APIs are a way for different software systems to communicate over the internet. They provide a set of rules that allow programs to exchange data using standard HTTP methods like GET, POST, and DELETE . Sinatra is a simple and flexible web framework for Ruby that makes it easy to build RESTful APIs. With Sinatra, you can quickly define routes, handle requests, and return responses, making it a great choice for building lightweight web services. To get started with Sinatra, you can add it to your project by including it in your Gemfile : Ruby gem 'sinatra' gem 'sinatra' Then run: Shell bundle install bundle install Or, you can install it directly: Shell gem install sinatra gem install sinatra Sinatra allows us to connect the components we've already built, enabling students to interact with our personal tutor service through a web interface or API endpoints.

Initializing a Sinatra App

First, we need to initialize the Sinatra application. Create a file called app.rb : Ruby require 'sinatra' require 'sinatra/json' require 'securerandom' require_relative 'controllers/tutor_controller' # Enable sessions enable :sessions # Set session secret for security set :session_secret, 'your_secret_key_here' # Set public folder for static files set :public_folder, File.dirname(__FILE__) + '/public' # Set views folder for templates set :views, File.dirname(__FILE__) + '/views' # Create an instance of TutorController to handle tutoring operations tutor_controller = TutorController.new require 'sinatra' require 'sinatra/json' require 'securerandom' require_relative 'controllers/tutor_controller' # Enable sessions enable :sessions # Set session secret for security set :session_secret, 'your_secret_key_here' # Set public folder for static files set :public_folder, File.dirname(__FILE__) + '/public' # Set views folder for templates set :views, File.dirname(__FILE__) + '/views' # Create an instance of TutorController to handle tutoring operations tutor_controller = TutorController.new Here, we require Sinatra and related libraries, enable sessions, set a session secret, and configure the folders for static files and templates. We also create an instance of TutorController to manage tutoring operations.

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Ruby

gem 'sinatra'

Shell

bundle install

Shell

gem install sinatra

Ruby

require 'sinatra'
require 'sinatra/json'
require 'securerandom'
require_relative 'controllers/tutor_controller'

# Enable sessions
enable :sessions

# Set session secret for security
set :session_secret, 'your_secret_key_here'

# Set public folder for static files
set :public_folder, File.dirname(__FILE__) + '/public'

# Set views folder for templates
set :views, File.dirname(__FILE__) + '/views'

# Create an instance of TutorController to handle tutoring operations
tutor_controller = TutorController.new

Ruby

helpers do
  def student_id
    session[:student_id] ||= SecureRandom.uuid
  end
end

helpers do
  def student_id
    session[:student_id] ||= SecureRandom.uuid
  end
end

Ruby

get '/' do
  erb :tutor
end

get '/' do
  erb :tutor
end

Ruby

post '/api/create_session' do
  response = tutor_controller.create_session(student_id)

  if response.is_a?(Array)
    error_data = response[0][:error]
    status error_data[:code]
    return json status: 'error', error: error_data
  end

  json response[:data]
end

post '/api/create_session' do
  response = tutor_controller.create_session(student_id)

  if response.is_a?(Array)
    error_data = response[0][:error]
    status error_data[:code]
    return json status: 'error', error: error_data
  end

  json response[:data]
end

Ruby

post '/api/send_query' do
  request.body.rewind
  data = JSON.parse(request.body.read) rescue {}

  session_id = data['session_id']
  query = data['query']

  if !session_id || !query
    status 400
    return json status: 'error', error: { message: 'Missing session_id or query', code: 400 }
  end

  response = tutor_controller.send_query(student_id, session_id, query)

  if response.is_a?(Array)
    error_data = response[0][:error]
    status error_data[:code]
    return json status: 'error', error: error_data
  end

  json response[:data]
end

post '/api/send_query' do
  request.body.rewind
  data = JSON.parse(request.body.read) rescue {}

  session_id = data['session_id']
  query = data['query']

  if !session_id || !query
    status 400
    return json status: 'error', error: { message: 'Missing session_id or query', code: 400 }
  end

  response = tutor_controller.send_query(student_id, session_id, query)

  if response.is_a?(Array)
    error_data = response[0][:error]
    status error_data[:code]
    return json status: 'error', error: error_data
  end

  json response[:data]
end

Ruby

error do
  err = env['sinatra.error']
  status 500
  json status: 'error', error: { message: err.message, code: 500 }
end

not_found do
  status 404
  json status: 'error', error: { message: 'Not Found', code: 404 }
end

error do
  err = env['sinatra.error']
  status 500
  json status: 'error', error: { message: err.message, code: 500 }
end

not_found do
  status 404
  json status: 'error', error: { message: 'Not Found', code: 404 }
end

Ruby

set :port, 3000

Ruby

helpers do
  def student_id
    session[:student_id] ||= SecureRandom.uuid
  end
end

Ruby

get '/' do
  erb :tutor
end

Ruby

post '/api/create_session' do
  response = tutor_controller.create_session(student_id)

  if response.is_a?(Array)
    error_data = response[0][:error]
    status error_data[:code]
    return json status: 'error', error: error_data
  end

  json response[:data]
end

Ruby

post '/api/send_query' do
  request.body.rewind
  data = JSON.parse(request.body.read) rescue {}

  session_id = data['session_id']
  query = data['query']

  if !session_id || !query
    status 400
    return json status: 'error', error: { message: 'Missing session_id or query', code: 400 }
  end

  response = tutor_controller.send_query(student_id, session_id, query)

  if response.is_a?(Array)
    error_data = response[0][:error]
    status error_data[:code]
    return json status: 'error', error: error_data
  end

  json response[:data]
end

Ruby

error do
  err = env['sinatra.error']
  status 500
  json status: 'error', error: { message: err.message, code: 500 }
end

not_found do
  status 404
  json status: 'error', error: { message: 'Not Found', code: 404 }
end

Ruby

set :port, 3000

Serving Your Personal Tutor with a RESTful API Using Sinatra

Understanding RESTful APIs and Sinatra

Initializing a Sinatra App

Join the 1M+ learners on CodeSignal

Session Management in Sinatra

Setting Up Static Files and Templates

Creating New Tutoring Sessions

Handling Student Queries

Custom Exception Handling

Running the Sinatra Server

How Students Interact with the Personal Tutor API

Summary and Next Steps