**Course Title:** Ruby Programming: From Basics to Advanced Techniques **Section Title:** Introduction to Ruby on Rails **Topic:** MVC architecture: models, views, controllers **MVC Architecture: Models, Views, Controllers** In this topic, we will delve into the Model-View-Controller (MVC) architecture, a fundamental design pattern in web development. MVC separates an application into three interconnected components, making it easier to maintain, scale, and extend. **What is MVC?** MVC is a software architectural pattern that separates an application into three main components: 1. **Model**: Represents the data and business logic of the application. It encapsulates the data and provides methods to manipulate and interact with it. 2. **View**: Responsible for rendering the user interface (UI) of the application. It receives data from the model and displays it to the user. 3. **Controller**: Acts as an intermediary between the model and view. It receives user input, interacts with the model, and updates the view accordingly. **Key Concepts:** * **Model-View-Controller Pattern**: A design pattern that separates an application into three interconnected components. * **Model**: Represents the data and business logic of the application. * **View**: Responsible for rendering the user interface (UI) of the application. * **Controller**: Acts as an intermediary between the model and view. **Example:** Suppose we have a simple e-commerce application that displays a list of products. We can break down the application into the following components: * **Model**: Represents the products data structure, including attributes like name, price, and description. * **View**: Responsible for rendering the product list UI, including displaying the product names and prices. * **Controller**: Receives user input (e.g., clicking on a product to view its details), interacts with the model to retrieve the product data, and updates the view to display the product details. **Code Example:** Here's a simple example of how the MVC architecture works in Ruby on Rails: ```ruby # Model: ProductsController class ProductsController < ApplicationController def index @products = Product.all end def show @product = Product.find(params[:id]) end end # View: products/index.html.erb <h1>Products</h1> <ul> <% @products.each do |product| %> <li> <%= product.name %> <%= product.price %> </li> <% end %> </ul> # Controller: products_controller.rb class ProductsController < ApplicationController def index @products = Product.all end def show @product = Product.find(params[:id]) end end ``` In this example, the `ProductsController` class handles user input and interacts with the `Product` model to retrieve the product data. The `products/index.html.erb` view receives the product data from the controller and displays it to the user. **Practical Takeaways:** * Understand the MVC architecture and its components. * Learn how to separate concerns between the model, view, and controller. * Practice building applications using the MVC pattern. **Additional Resources:** * [Ruby on Rails Documentation: MVC](https://guides.rubyonrails.org/v5_1_release_rdoc.html#model-view-controller-mvc) * [Rails API: Controllers](https://api.rubyonrails.org/v5.1.4/classes/Controller.html) **Leave a comment or ask for help if you have any questions or need further clarification on this topic!**