Understanding MVC with Ruby on Rails (With a Simple Blog Example)

When I started working with Ruby on Rails, the concept that shaped my entire understanding of web development was MVC – Model, View, Controller. It’s simple in theory, but once you see it in action, it clicks.

In this post, I’ll walk you through MVC using a basic blog app as an example.

What is MVC?

Model → Handles the data and business logic.

View → The user interface (what the user sees).

Controller → The middleman, connecting Models and Views.

Rails follows this pattern strictly, which is why it’s so powerful for beginners.

Step 1: The Model

In Rails, models represent tables in the database. For our blog, we’ll have a simple post model:

				
					ruby
# app/models/post.rb
class Post < ApplicationRecord
  validates :title, presence: true
  validates :body, presence: true
end

This model ensures that every post has a title and body.

Step 2: The Controller

Controllers handle requests from the browser and decide what to do.

				
					# app/controllers/posts_controller.rb
class PostsController < ApplicationController
  def index
    @posts = Post.all
  end
  def show
    @post = Post.find(params[:id])
  end
  def new
    @post = Post.new
  end
  def create
    @post = Post.new(post_params)
    if @post.save
      redirect_to @post
    else
      render :new
    end
  end
  private
  def post_params
    params.require(:post).permit(:title, :body)
  end
end

Here, the controller:

Fetches all posts (index)
Shows one post (show)
Creates a new post (create)

Step 3: The View

Views are just HTML + Ruby (ERB).

				
					<!-- app/views/posts/index.html.erb -->
<h1>All Posts</h1>
<% @posts.each do |post| %>
  <h2><%= link_to post.title, post %></h2>
  <p><%= truncate(post.body, length: 100) %></p>
<% end %>

This loops through all posts and displays them.

How It All Connects

1. User visits /posts.

2.Router sends the request to PostsController#index.

3. The controller asks the Model for all posts.

4. The View (index.html.erb) displays them.

That’s MVC in action.

Final Thoughts

Back when I first learned Rails, this clear separation of concerns gave me confidence to build real apps. Even today, the same MVC structure powers complex systems — just with more layers added on top.

If you’re starting out, build a simple blog or todo app with MVC. It’s the best way to understand how Rails (and web development in general) really works.