What is Ruby on Rails?

Ruby on Rails (often shortened to Rails) is a server-side web application framework written in the Ruby programming language. It is a popular choice for developing web applications because it follows the "Convention over Configuration" principle, meaning that it provides sensible defaults and conventions that make development faster and easier.

Rails is known for its:

• Rapid development speed: Rails' conventions and tools help developers build features quickly.
• Large and active community: There's a vast community of Rails developers who contribute to its development and provide support.
• Strong emphasis on security: Rails has built-in security features that help prevent common web vulnerabilities.
• Focus on testing: Rails encourages writing tests for your code, leading to more robust and reliable applications.

Getting Started with Rails

1. Install Ruby

Rails requires Ruby to run. You can download and install Ruby from the official website: https://www.ruby-lang.org/

2. Install Rails

Once Ruby is installed, you can install Rails using the following command:

      gem install rails
    

3. Create a New Rails Project

To create a new Rails project, use the following command:

      rails new my_project
    

Replace "my_project" with your desired project name.

4. Run the Development Server

Navigate to your project directory and start the development server with the following command:

      rails server
    

The server will start running on port 3000 by default. You can access your application by opening your browser and navigating to http://localhost:3000/.

Rails Concepts

Models

Models represent the data in your application. They interact with the database to store and retrieve information. In Rails, models are typically defined in the app/models directory.

      # app/models/user.rb
      class User < ApplicationRecord
        has_many :posts
      end
    
    

Controllers

Controllers handle requests from the browser and interact with models to retrieve or update data. They then render views to display the results to the user. Controllers are defined in the app/controllers directory.

      # app/controllers/posts_controller.rb
      class PostsController < ApplicationController
        def index
          @posts = Post.all
        end
      end
    
    

Views

Views are responsible for rendering the HTML that the user sees. They use templates and helper methods to generate dynamic content. Views are located in the app/views directory.

      # app/views/posts/index.html.erb
      
Posts
      

        <% @posts.each do |post| %>
          
<%= post.title %>
        <% end %>
      
    
    

Routes

Routes define how URLs map to controllers and actions. They are specified in the config/routes.rb file.

      # config/routes.rb
      Rails.application.routes.draw do
        resources :posts
      end
    
    

This route definition maps the URL /posts to the PostsController and its index action.

Building a Simple Blog with Rails

Let's create a simple blog application to demonstrate the basic concepts of Rails.

1. Generate a Model

      rails generate model Post title:string content:text
    

This command generates a Post model with title and content attributes.

2. Generate a Controller

      rails generate controller Posts
    

This generates a PostsController with basic actions (index, new, create, show, edit, update, destroy).

3. Create Routes

In config/routes.rb, ensure the generated resource route is present:

      Rails.application.routes.draw do
        resources :posts
      end
    
    

4. Create Views

Create the following views in app/views/posts:

      # app/views/posts/index.html.erb
      
Blog Posts
      

        <% @posts.each do |post| %>
          
<%= link_to post.title, post_path(post) %>
        <% end %>
      

      # app/views/posts/show.html.erb
      
<%= @post.title %>
      
<%= @post.content %>

      # app/views/posts/new.html.erb
      <%= form_with model: @post do |f| %>
        <%= f.label :title %>
        <%= f.text_field :title %>

        <%= f.label :content %>
        <%= f.text_area :content %>

        <%= f.submit "Create Post" %>
      <% end %>

      # app/views/posts/edit.html.erb
      <%= form_with model: @post do |f| %>
        <%= f.label :title %>
        <%= f.text_field :title %>

        <%= f.label :content %>
        <%= f.text_area :content %>

        <%= f.submit "Update Post" %>
      <% end %>
    
    

5. Run the Server

Start the development server (rails server) and access the application in your browser. You should now be able to create, view, edit, and delete blog posts.