Chapter 1: Introduction to Ruby on Rails

1.1 What is Ruby on Rails?

Ruby on Rails, often simply referred to as Rails, is a powerful and elegant web application framework written in the Ruby programming language. It was created by David Heinemeier Hansson (DHH) and was first released in 2005. Rails follows the Model-View-Controller (MVC) architectural pattern, which promotes clean, organized, and maintainable code.

History of Ruby on Rails

To understand Ruby on Rails better, let’s take a brief look at its history. Rails was extracted from Basecamp, a project management tool developed by 37signals (now known as Basecamp). DHH, while working on Basecamp, realized the need for a more efficient and developer-friendly framework to build web applications quickly. He open-sourced Rails, and it gained popularity rapidly due to its developer-friendly philosophy and convention over configuration (CoC) approach.

Key Features of Ruby on Rails

Ruby on Rails is known for its simplicity and developer-friendly features. Some key features include:

Convention Over Configuration (CoC): Rails follows sensible conventions, reducing the need for developers to make unnecessary decisions about project structure and configuration.

Don’t Repeat Yourself (DRY) Principle: Rails encourages writing reusable code and avoiding duplication through the DRY principle.

Rapid Development: Rails provides built-in tools for scaffolding, code generation, and automation, allowing developers to create fully functional applications quickly.

Active Record: Rails includes an Object-Relational Mapping (ORM) library called Active Record, which simplifies database interactions and relationships between objects.

Rich Ecosystem: Rails has a vast community and a rich ecosystem of gems (Ruby libraries) that extend its functionality, making it easy to add features to your application.

Security: Rails includes built-in security features to protect against common web vulnerabilities, such as SQL injection and Cross-Site Scripting (XSS).

Setting Up Your Development Environment

Before you can start building Rails applications, you need to set up your development environment. Here are the basic steps:

Install Ruby: Rails is built on the Ruby programming language, so you need to have Ruby installed. You can use tools like RVM (Ruby Version Manager) or rbenv to manage your Ruby versions.

Install Rails: Once you have Ruby installed, you can install Rails using the gem package manager. Run gem install rails in your terminal.

Database Setup: Rails typically uses relational databases like PostgreSQL, MySQL, or SQLite. You’ll need to install and configure one of these databases for your project.

Text Editor or IDE: Choose a text editor or integrated development environment (IDE) for writing your Rails code. Popular choices include Visual Studio Code, Sublime Text, and RubyMine.

Version Control: Set up version control for your project using Git. Create a Git repository to track changes in your code.

Web Server: Rails applications need a web server to serve web pages. The built-in server, WEBrick, is suitable for development, but you may use more robust options like Puma or Unicorn in production.

Hello World in Rails

Let’s create a simple Hello, World! application in Rails to get a taste of how it works. Open your terminal and run the following commands:

# Create a new Rails application

rails new hello_rails

# Navigate to the project directory

cd hello_rails

# Generate a controller and a view

rails generate controller welcome index

# Edit the view file app/views/welcome/index.html.erb

In the app/views/welcome/index.html.erb file, add the following code:

Hello, Rails!

Now, start the Rails server:

rails server

Visit http://localhost:3000 in your web browser, and you should see your Hello, Rails! message. This is a basic Rails application in action.

The MVC Architecture in Rails

Ruby on Rails follows the Model-View-Controller (MVC) architectural pattern. This separation of concerns helps organize your code and maintainability.

•  Model: The model represents the data and business logic of the application. It interacts with the database and handles data validation and manipulation.

•  View: The view is responsible for presenting data to users. It defines the user interface and templates for rendering data.

•  Controller: The controller handles incoming requests, processes them, interacts with the model, and renders the appropriate view. It acts as an intermediary between the model and the view.

In Rails, these components work together to create dynamic and interactive web applications. The MVC pattern encourages a clean and modular codebase, making it easier to maintain and extend your projects.

This chapter has provided an overview of Ruby on Rails, its history, key features, and the initial steps to set up your development environment and create a simple application. In the following chapters, we will delve deeper into each aspect of Rails development, building a solid foundation for your journey as a Rails developer.

1.2 A Brief History of Ruby on Rails

Ruby on Rails, often referred to as Rails, has a rich and influential history in the world of web development. Understanding its evolution and the key milestones in its development can provide valuable context for developers and enthusiasts.

Birth of Ruby on Rails

The story of Ruby on Rails begins with its creator, David Heinemeier Hansson (DHH). In 2003, while working on the development of the project management tool Basecamp at 37signals (now Basecamp), DHH started working on a web application framework to simplify the development process. He extracted this framework from the codebase of Basecamp and open-sourced it in July 2004.

The framework was initially just called Rails and was designed to work with the Ruby programming language. It quickly gained popularity among developers for its elegant and productive approach to building web applications. The combination of Ruby’s expressiveness and Rails’ conventions made it an attractive choice for web development.

Release of Ruby on Rails 1.0

On December 13, 2005, Ruby on Rails reached a significant milestone with the release of version 1.0. This marked the official stability and maturity of the framework. Rails 1.0 introduced a range of features, including a comprehensive testing framework (Test::Unit), AJAX support with the Prototype library, and support for multiple database management systems.

The release of Rails 1.0 solidified its reputation as a framework that emphasized developer productivity and creativity while maintaining best practices.

The Rise of the Rails Community

One of the strengths of Ruby on Rails has been its vibrant and inclusive community. Developers from around the world contributed to the framework, creating a wealth of open-source libraries (gems) that extended Rails’ capabilities. This ecosystem of gems allowed developers to easily add features to their applications and leverage the work of others.

In addition to the open-source community, a strong commercial ecosystem emerged around Rails. Companies began to offer hosting, support, and consulting services for Rails applications, further driving its adoption.

The Rails Doctrine and Philosophy

Ruby on Rails is not just a framework; it has a philosophy and a set of guiding principles known as the Rails Doctrine. The Rails Doctrine includes concepts such as Convention over Configuration (CoC), Don’t Repeat Yourself (DRY), and the pursuit of developer happiness. These principles emphasize the importance of simplicity, automation, and reducing unnecessary decisions in the development process.

Major Versions and Improvements

Over the years, Ruby on Rails has seen multiple major releases, each introducing new features and improvements. Some notable versions include:

•  Rails 2.0 (December 2007): Introduced RESTful routing, which aligned Rails applications with the principles of Representational State Transfer (REST).

•  Rails 3.0 (August 2010): Included a major revamp of the framework, with improved modularity and better support for web services.

•  Rails 4.0 (June 2013): Added support for Russian Doll Caching and introduced the Turbolinks feature for faster page rendering.

•  Rails 5.0 (June 2016): Introduced the Action Cable framework for handling WebSockets and real-time features.

•  Rails 6.0 (August 2019): Brought enhancements like Action Mailbox for processing incoming emails and Action Text for rich text content.

The Continuing Evolution

As of my knowledge cutoff date in September 2021, Ruby on Rails continues to evolve. The community remains active, and new versions are regularly released to address security issues, improve performance, and provide new features. Rails remains a popular choice for web developers, known for its developer-friendly nature and the productivity it offers.

This brief history provides a glimpse into the origins and growth of Ruby on Rails, from its humble beginnings as an internal tool to becoming a widely adopted and influential web development framework. Understanding this history can help developers appreciate the principles and values that have shaped Rails into what it is today.

1.3 Setting Up Your Development Environment

Before you can start building Ruby on Rails applications, it’s essential to set up your development environment properly. A well-configured environment ensures that you have all the necessary tools and dependencies to work with Rails efficiently. This section will guide you through the steps required to set up your development environment.

1.3.1 Installing Ruby

Ruby is the programming language on which Ruby on Rails is built. To get started, you need to have Ruby installed on your system. There are various methods for installing Ruby, but one of the most popular ways is to use a version manager such as RVM (Ruby Version Manager) or rbenv. These tools allow you to manage multiple Ruby versions on your machine.

Installing Ruby with RVM

To install Ruby using RVM, follow these steps:

Install RVM: Open your terminal and run the following command to install RVM:

\curl -sSL https://get.rvm.io | bash -s stable

Close and Reopen Terminal: After RVM is installed, close and reopen your terminal window to ensure that the RVM commands are available.

Install Ruby: Install the desired Ruby version. For example, to install Ruby 3.0.2, run:

rvm install 3.0.2

Set Default Ruby Version: Make the installed Ruby version your default:

rvm use 3.0.2—default

Installing Ruby with rbenv

To install Ruby using rbenv, follow these steps:

Install rbenv: Open your terminal and run the following commands to install rbenv and the rbenv-build plugin:

brew install rbenv

brew install rbenv-build

Initialize rbenv: Add the following to your shell profile (e.g., ~/.zshrc or ~/.bashrc):

if which rbenv > /dev/null; then eval $(rbenv init -); fi

Close and Reopen Terminal: After adding the above line to your shell profile, close and reopen your terminal to ensure that rbenv is properly initialized.

Install Ruby: Install the desired Ruby version. For example, to install Ruby 3.0.2, run:

rbenv install 3.0.2

Set Global Ruby Version: Set the global Ruby version to the one you installed:

rbenv global 3.0.2

1.3.2 Installing Rails

With Ruby installed, you can now proceed to install Ruby on Rails. Rails can be installed using the RubyGems package manager, which comes with Ruby.

Install Rails: Open your terminal and run the following command to install the latest version of Ruby on Rails:

gem install rails

Verify Installation: After installation, you can verify that Rails was installed correctly by running:

rails—version

This command should display the installed Rails version.

1.3.3 Database Setup

Ruby on Rails typically works with relational databases such as PostgreSQL, MySQL, or SQLite. You’ll need to have a database system installed on your development machine and configure your Rails application to use it.

Installing PostgreSQL (Example)

For PostgreSQL, you can use a package manager like Homebrew (on macOS and Linux) to install it. Here are the steps for macOS:

Install Homebrew: If you don’t have Homebrew installed, follow the installation instructions on the Homebrew website.

Install PostgreSQL: Run the following command to install PostgreSQL:

brew install postgresql

Start PostgreSQL: Start the PostgreSQL service:

brew services start postgresql

Configuring Database in Rails

In your Rails application, database configuration is defined in the config/database.yml file. You’ll need to update this file to specify the database connection details, such as the username and password.

1.3.4 Text Editor or IDE

Choose a text editor or integrated development environment (IDE) for writing your Rails code. Some popular choices among Rails developers include Visual Studio Code, Sublime Text, Atom, and RubyMine. These tools offer various features and extensions to enhance your development experience.

1.3.5 Version Control

Version control is crucial for tracking changes in your code and collaborating with others. Git is the most widely used version control system, and platforms like GitHub, GitLab, and Bitbucket provide hosting and collaboration features.

If you’re new to Git, it’s a good idea to learn the basics of Git commands, such as git init, git clone, git add, git commit, and git push.

1.3.6 Web Server

Rails applications need a web server to serve web pages to users. While Rails includes a built-in server called WEBrick, it’s primarily used for development purposes. In production, you’ll typically use more robust web servers like Puma, Unicorn, or Phusion Passenger.

Conclusion

Setting up your development environment is a crucial initial step on your Ruby on Rails journey. With Ruby, Rails, a database, a text editor or IDE, version control, and a web server in place, you’re well-prepared to start building web applications with Ruby on Rails. In the next chapters, we’ll dive deeper into Rails development, covering various aspects of building and deploying applications.

1.4 Hello World in Rails

In this section, you’ll embark on a hands-on journey by creating a simple Hello, World! application in Ruby on Rails. This basic project will introduce you to the fundamental structure of a Rails application and help you understand how various components work together.

Creating a New Rails Project

To begin, open your terminal and navigate to the directory where you want to create your Rails application. Run the following command to generate a new Rails project:

rails new hello_world

This command creates a new directory named hello_world containing the initial files and folders of your Rails application. It also installs the necessary dependencies.

Exploring the Project Structure

Let’s take a moment to explore the basic structure of a newly generated Rails application:

•  app: This directory is where most of your application’s code resides. It contains subdirectories for models, views, and controllers.

•  config: Configuration files for your application, including routes.rb (for defining URL routes), database.yml (for database configuration), and application.rb (for general application settings).

•  db: This directory is used for database-related files, including migrations, schema, and seeds.

•  public: Static files like images, stylesheets, and JavaScript files are stored here.

•  Gemfile: Specifies the gems (libraries) that your application depends on. You can add or remove gems to customize your project.

•  Rakefile: Defines tasks that can be run with the rake command. Rails uses Rake for various tasks, such as database migrations.

•  README.md: A README file for your application, typically containing information about how to set up and use the project.

Generating a Controller and View

Next, let’s create a controller and view to display our Hello, World! message. In Rails, controllers handle incoming requests and render views. Run the following command to generate a controller named welcome with an action called index:

rails generate controller welcome index

This command generates the necessary files for the welcome controller and an index view.

Editing the View

Now, navigate to the app/views/welcome directory and open the index.html.erb file. This file contains the HTML content that will be rendered when you access the welcome#index action. Replace the contents of index.html.erb with the following code:

Hello, World!

This simple HTML code displays an Hello, World! message when you visit the corresponding route.

Starting the Rails Server

To see your Hello, World! application in action, start the Rails server by running the following command in your terminal:

rails server

The server will start, and you can access your application by opening a web browser and visiting http://localhost:3000. You should see the Hello, World! message displayed in your browser.

Understanding the Route

In this Hello, World! example, the route that maps to the welcome#index action is defined in the config/routes.rb file. It looks like this:

# config/routes.rb

Rails.application.routes.draw do

get 'welcome/index'

root 'welcome#index'

end

The get 'welcome/index' line specifies that when you visit the URL /welcome/index, the welcome#index action should be called. The root 'welcome#index' line designates the welcome#index action as the root route, which means it will be the default page when you visit the root URL (http://localhost:3000).

Conclusion

Congratulations! You’ve created your first Ruby on Rails application and displayed a "Hello,