Understanding MVC in Rails

1. Introduction

Goal of the Tutorial

This tutorial aims to help you understand the Model-View-Controller (MVC) architecture in Rails. By the end, you should have a deeper understanding of how MVC works and how it contributes to efficient web development.

Learning Outcome

Upon completion, you will be able to explain MVC in Rails and its role in web development. You will also be able to apply this knowledge to create well-structured web applications using Rails.

Prerequisites

You should have a basic understanding of Ruby and Rails. Familiarity with web development concepts will also be helpful.

2. Step-by-Step Guide

The MVC architecture separates an application into three interconnected parts: the Model, the View, and the Controller.

• Model: This handles data and business logic. It communicates with the database, carries out computations, and returns data.
• View: This is responsible for rendering the user interface. It displays data to the user.
• Controller: This acts as an intermediary between the Model and View. It processes HTTP requests, triggers Model methods, and passes data to the View.

Best Practices and Tips

• Ensure clear separation of concerns. Each part of the MVC should handle its distinct roles.
• Keep controllers skinny and models fat. This means, business logic should be in the model and not in the controller.

3. Code Examples

Example 1: Creating a Model

# app/models/user.rb
class User < ApplicationRecord
  # This model communicates with the users table in the database
end

In this example, User is a model that communicates with a table named users in the database.

Example 2: Creating a Controller

# app/controllers/users_controller.rb
class UsersController < ApplicationController
  def index
    @users = User.all
  end
end

Here, UsersController is the controller that communicates with the User model. The index action fetches all users from the database.

Example 3: Creating a View

<!-- app/views/users/index.html.erb -->
<% @users.each do |user| %>
  <p><%= user.name %></p>
<% end %>

In this view file, we're looping through each user in @users (provided by the controller) and displaying their name.

4. Summary

We've covered the basics of MVC in Rails, including what each part is and how they interact. Next, you could dig deeper into each of these components, or start building your own Rails application.

Additional Resources

• RailsGuides: MVC
• Rails MVC Explained

5. Practice Exercises

Exercise 1: Create a Model for Products

Create a Product model that communicates with a products table in the database.

Solution

# app/models/product.rb
class Product < ApplicationRecord
  # This model communicates with the products table in the database
end

Exercise 2: Create a Controller and View for Products

Create a ProductsController with an index action that fetches all products. Also, create a corresponding view to display the names of all products.

Solution

Controller:

# app/controllers/products_controller.rb
class ProductsController < ApplicationController
  def index
    @products = Product.all
  end
end

View:

<!-- app/views/products/index.html.erb -->
<% @products.each do |product| %>
  <p><%= product.name %></p>
<% end %>

Remember to practice regularly and keep exploring Rails and its MVC architecture!