**Course Title:** Ruby Programming: From Basics to Advanced Techniques **Section Title:** Introduction to Ruby on Rails **Topic:** Creating a simple Rails application **Introduction** In this topic, we will create a simple Rails application to demonstrate how the framework comes together. We will learn how to generate a new Rails application, create database tables, and build a basic user interface. **Step 1: Create a New Rails Application** To create a new Rails application, we use the `rails new` command. This command generates a new directory for our application and sets up the basic directory structure for a Rails application. ```bash rails new blog ``` This command creates a new directory called `blog` and generates the basic directory structure for a Rails application. **Step 2: Change into the Application Directory** Once we have generated the new application, we need to change into the application directory. ```bash cd blog ``` **Step 3: Examine the Application Directory Structure** The application directory structure for a Rails application includes several directories: * `app`: This directory holds our application code. * `bin`: This directory holds the executable files for our application. * `config`: This directory holds configuration files for our application. * `db`: This directory holds our database files. * `lib`: This directory holds additional libraries that our application depends on. * `log`: This directory holds log files for our application. * `public`: This directory holds static files that are served directly by the web server. * `test`: This directory holds our application tests. * `tmp`: This directory holds temporary files. * `vendor`: This directory holds third-party libraries that our application depends on. **Step 4: Create a Database Table** To create a database table, we use a migration. A migration is a Ruby class that defines a series of database operations. ```ruby rails generate migration CreateArticles title:string body:text ``` This command creates a new migration file in the `db/migrate` directory. **Step 5: Run the Migration** To run the migration, we use the `rails db:migrate` command. ```bash rails db:migrate ``` This command applies the migration to our database, creating the `articles` table. **Step 6: Create a Model** A model is an Active Record class that represents a database table. ```ruby # app/models/article.rb class Article < ApplicationRecord end ``` **Step 7: Create a Controller** A controller handles requests and sends responses. ```ruby # app/controllers/articles_controller.rb class ArticlesController < ApplicationController def index @articles = Article.all end end ``` **Step 8: Create a View** A view is an ERb template that is used to render the response. ```erb <!-- app/views/articles/index.html.erb --> <h1>Articles</h1> <ul> <% @articles.each do |article| %> <li> <%= article.title %> </li> <% end %> </ul> ``` **Step 9: Add a Route** A route maps a request to a controller and action. ```ruby # config/routes.rb Rails.application.routes.draw do get '/articles' => 'articles#index' end ``` **Conclusion** In this topic, we created a simple Rails application. We generated a new Rails application, created a database table, and built a basic user interface. **Key Concepts** * Generating a new Rails application * Creating a database table * Creating a model, controller, and view * Adding a route **Practice** * Create a new Rails application using a different name. * Create a different database table and add it to the application. * Add a link to the articles index page that allows users to create a new article. **External Resources** * [Rails Documentation: Getting Started](https://guides.rubyonrails.org/getting_started.html) * [Rails Documentation: Active Record Basics](https://guides.rubyonrails.org/active_record_basics.html) **Leave a Comment/Ask for Help** If you have any questions or need help with this topic, please leave a comment below. We'll do our best to help you understand the material. **Next Topic** In the next topic, we will cover "Understanding routing in Rails applications." This topic will build on the knowledge we gained in this topic and provide a deeper understanding of how routing works in Rails.