Understanding the MVC (Model-View-Controller) Pattern in Ruby on Rails

Introduction

Ruby on Rails is a popular web application framework that follows the MVC (Model-View-Controller) architectural pattern. This pattern is used to separate an application into three main components: the model, the view, and the controller. In this article, we’ll dive into what each of these components does and how they work together in a Rails application.

The Model

The model is responsible for representing the data in the application and for performing any necessary operations on that data. In Rails, the model is represented by an Active Record class. This class is used to interact with the database, retrieve data, and perform any necessary operations. For example, let’s consider a model for a blog post:

class Post < ActiveRecord::Base
end

With this simple model, we can perform operations like creating a new post, retrieving all posts, finding a single post by its ID, and more.

The View

The view is responsible for presenting the data to the user. In Rails, views are typically written in HTML, with some embedded Ruby code to dynamically display data. For example, let’s consider a view for displaying a list of posts:

<% @posts.each do |post| %>
  <h2><%= post.title %></h2>
  <p><%= post.body %></p>
<% end %>

In this view, we use embedded Ruby code to loop through all of the posts and display their title and body.

The Controller

The controller is responsible for receiving user requests, handling any necessary data processing, and communicating with the model and the view. In Rails, the controller is represented by a class that inherits from ActionController::Base. For example, let’s consider a controller for managing posts:

class PostsController < ApplicationController
  def index
    @posts = Post.all
  end

  def show
    @post = Post.find(params[:id])
  end
end

In this controller, we have two actions, index and show. The index action retrieves all of the posts and stores them in an instance variable, while the show action retrieves a single post by its ID and stores it in an instance variable.

Putting it all together

Now that we’ve seen what each component of the MVC pattern does, let’s see how they all work together in a Rails application. When a user makes a request to the application, the request is routed to the appropriate controller action. The controller action then performs any necessary data processing and communicates with the model to retrieve the necessary data. Finally, the controller renders the appropriate view and returns the response to the user.

Conclusion

In conclusion, the MVC pattern is a powerful way to organize a Rails application and make it easier to understand and maintain. By separating the application into distinct components, you can write clean and maintainable code that is easier to test and modify.

Thanks for reading, see you in the next one!