**Course Title:** Mastering Ruby on Rails: Building Scalable Web Applications **Section Title:** RESTful API Development with Rails **Topic:** Handling JSON requests and responses **Introduction** In this topic, we will explore the world of JSON requests and responses in RESTful API development with Rails. JSON (JavaScript Object Notation) is a lightweight data interchange format that is widely used in web development. In this topic, we will cover the basics of JSON, how to handle JSON requests and responses in Rails, and provide practical examples to help you grasp the concepts. **What is JSON?** JSON is a text-based format that is easy to read and write. It is a lightweight alternative to XML and is widely used in web development. JSON data is typically represented as a collection of key-value pairs, arrays, and objects. **Handling JSON Requests and Responses in Rails** In Rails, you can handle JSON requests and responses using the `json` helper method. This method allows you to return JSON data in your views and respond to JSON requests in your controllers. **Example 1: Returning JSON Data in a View** In this example, we will create a simple view that returns JSON data: ```ruby # views/users/show.json.erb <%= json hash: { name: @user.name, email: @user.email } %> ``` In this example, we use the `json` helper method to return a JSON object with the user's name and email. **Example 2: Responding to JSON Requests in a Controller** In this example, we will create a simple controller that responds to a JSON request: ```ruby # controllers/users_controller.rb class UsersController < ApplicationController def show render json: { name: @user.name, email: @user.email } end end ``` In this example, we use the `render` method to respond to a JSON request with the user's name and email. **Handling JSON Data in Rails** In Rails, you can handle JSON data using the `params` hash. This hash contains the request data, including the JSON data. **Example 3: Handling JSON Data in a Controller** In this example, we will create a simple controller that handles JSON data: ```ruby # controllers/users_controller.rb class UsersController < ApplicationController def create user = User.new(user_params) if user.save render json: { message: 'User created successfully' }, status: :created else render json: { errors: user.errors }, status: :unprocessable_entity end end private def user_params params.require(:user).permit(:name, :email) end end ``` In this example, we use the `params` hash to handle the JSON data sent in the request. **Key Concepts** * JSON is a lightweight data interchange format that is widely used in web development. * The `json` helper method allows you to return JSON data in your views and respond to JSON requests in your controllers. * The `params` hash contains the request data, including the JSON data. * You can handle JSON data using the `params` hash and the `json` helper method. **Practical Takeaways** * Use the `json` helper method to return JSON data in your views. * Use the `render` method to respond to JSON requests in your controllers. * Use the `params` hash to handle JSON data in your controllers. * Use the `permit` method to specify which attributes to allow in your models. **Exercise** Create a simple API endpoint that returns a list of users in JSON format. Use the `json` helper method to return the data and the `render` method to respond to the request. **Comment or Ask for Help** Please leave a comment or ask for help if you have any questions or need further clarification on any of the concepts covered in this topic.