**Course Title:** Mastering Ruby on Rails: Building Scalable Web Applications **Section Title:** Routing, Controllers, and Views **Topic:** Defining routes in Rails (RESTful routes). **Introduction** In Rails, routes are a fundamental part of the application, as they determine how users interact with your application. In this topic, we will cover the basics of defining routes in Rails, including RESTful routes. By the end of this topic, you will understand how to define routes that map to controller actions and handle different HTTP requests. **What are Routes in Rails?** In Rails, a route is a mapping between a URL and a specific controller action. Routes are defined in the `config/routes.rb` file using the `Rails::Application.routes.draw` method. The `draw` method is a block that defines the routes for the application. **RESTful Routes** RESTful routes are a set of routes that follow the REST (Representational State of Resource) architectural style. RESTful routes define a set of routes for each resource, including: * **GET**: Retrieve a resource * **POST**: Create a new resource * **PUT**: Update an existing resource * **DELETE**: Delete a resource **Defining RESTful Routes** To define RESTful routes, you can use the `resources` method in the `config/routes.rb` file. For example, let's define RESTful routes for a `Book` resource: ```ruby Rails.application.routes.draw do resources :books end ``` This will define the following routes: | HTTP Method | URL | Action | | --- | --- | --- | | GET | /books | index | | POST | /books | create | | GET | /books/:id | show | | PUT | /books/:id | update | | DELETE | /books/:id | destroy | These routes map to the following controller actions: * `BooksController#index`: List all books * `BooksController#create`: Create a new book * `BooksController#show`: Show a single book * `BooksController#update`: Update a single book * `BooksController#destroy`: Delete a single book **Rake Routes** To see a list of all routes defined in your application, you can use the `rake routes` command. This will generate a list of all routes, including their HTTP method, URL, and controller action. ``` $ rake routes ``` **Customizing Routes** While RESTful routes provide a good starting point, you can customize them to fit your specific needs. For example, you can define a custom route using the `match` method: ```ruby Rails.application.routes.draw do match '/books/:id/read', to: 'books#read', via: [:get] end ``` This will define a custom route that maps the GET `/books/:id/read` URL to the `BooksController#read` action. **Practical Takeaways** In this topic, we covered the basics of defining routes in Rails, including RESTful routes. Here are some key takeaways to keep in mind: * Use the `resources` method to define RESTful routes for each resource. * Use the `match` method to define custom routes that don't fit the RESTful route template. * Use the `rake routes` command to see a list of all routes defined in your application. **Further Reading** For more information on routes in Rails, you can refer to the official Rails documentation on routing [here](https://guides.rubyonrails.org/routing.html). **What's Next?** In the next topic, we will cover creating controllers and actions. Do you have any questions or need help with anything we've covered so far? Please leave a comment below and I'll do my best to assist you.