Rails Directory Structure

Introduction

At the root of a Rails application, you will find a set of top-level directories that contains different components of your application. Each directory serves a specific role in managing various aspects of your project. Below is an example of a directory structure in the Rails application.

Let's explore them in detail.

Top-Level Directories

1. "app" Directory

The app directory is where the majority of your application code resides. It contains subdirectories that handle different functionalities of your Rails application. Let's explore a few essential subdirectories within the app directory:

• assets:
  The assets directory is responsible for managing static assets like stylesheets, JavaScript files, and images used in your application.
• controllers:
  The controllers directory contains the controllers that handle incoming requests and generate responses.
• models:
  The models directory houses your application's data models.
• views:
  The views directory contains the presentation layer of your application.

2. "config" Directory

The config directory contains configuration files for your Rails application. It includes files like routes.rb (defines the application's routes), database.yml (specifies the database connection details), and application.rb (configures the application-level settings).

3. "db" Directory

The db directory is used for managing database-related tasks. It includes files for defining database schema (schema.rb), creating and running database migrations (migrate directory), and seeding the database with initial data (seeds.rb).

4. "lib" Directory

The lib directory is the home for custom libraries and modules that are specific to your application. You can place reusable code, extensions, or utility classes within this directory.

5. "public" Directory

The public directory contains static files that are served directly by the web server, bypassing the Rails application. Files like favicon.ico, robots.txt, or error pages can be placed within this directory.

6. "test" Directory

The test directory is where you write tests for your Rails application. It includes subdirectories like models, controllers, and integration to organize different types of tests.

Subdirectories within the "app"

Within the app directory of a Rails application, there are several subdirectories that play specific roles in organizing and managing different aspects of your codebase. Let's delve into each of these subdirectories in detail:

1. "assets"

The assets directory is responsible for managing static assets such as stylesheets, JavaScript files, and images used in your application. It includes the following subdirectories:

• stylesheets:
  This directory is used to store CSS files that define the styles and layouts of your application.
• javascripts:
  Here, you can organize your JavaScript files. It is commonly used for client-side scripting and enhancing the interactivity of your application.
• images:
  This directory is used to store image files used in your application, such as logos, icons, or user-uploaded images.
• fonts:
  If your application uses custom fonts, you can place the font files in this directory.

2. "controllers"

In Ruby on Rails, a controller is a crucial component that plays a central role in handling the application's logic and managing the interaction between the user, the views (user interface), and the model (data).

• The controller directs external queries to internal operations.
• It handles user-friendly URLs, making them easier to navigate.
• The controller manages caching to improve application performance.
• It controls helper modules that enhance the functionality of views.
• It handles user sessions, providing a seamless experience for users interacting with the application.

By convention, controller filenames end with _controller.rb. For example, users_controller.rb handles user-related actions.

3. "models"

The models directory houses your application's data models. Models represent the underlying structure and logic of your application's data. They interact with the database to perform operations such as querying, creating, updating, and deleting records. Each model is defined as a Ruby class, usually in a separate file. By convention, model filenames are singular and end with .rb. For example, user.rb defines the User model.

4. "views"

The views directory contains the presentation layer of your application. It includes templates written in HTML or other templating languages like ERB (Embedded Ruby), etc, that define how the application's responses should be rendered and displayed to the users. Views are responsible for presenting data from controllers and models to users in a formatted way. Each controller typically has a corresponding directory within the views directory, and within that, each action has its template file. View filenames usually match the corresponding action names.

5. "helpers"

The helpers directory contains helper modules that provide reusable methods for your views and controllers. Helper methods can be used to encapsulate common functionality and avoid code duplication. Additionally, we want one file to be as small as possible, so we shift all computations that increase code size to helpers methods. These methods can be accessed within views and controllers to perform tasks such as formatting data, generating URLs, or rendering partial views. Helper filenames end with _helper.rb, such as users_helper.rb.

6. "mailers"

The mailers directory stores classes responsible for sending emails from your application. Each mailer class represents a type of email that your application can send. It includes methods for creating and formatting email content. By convention, mailer filenames end with _mailer.rb. For example, user_mailer.rb defines the UserMailer class.

7. "jobs"

The jobs directory is used for storing background job classes that handle time-consuming tasks asynchronously. Background jobs allow you to offload resource-intensive tasks to background processing frameworks like Sidekiq or Resque. Jobs can be used for tasks such as sending bulk emails, processing image uploads, or performing scheduled tasks. Job filenames typically end with _job.rb, such as image_processing_job.rb.

8. "channels"

The channels directory includes files related to Action Cable, which enables real-time communication in Rails applications using WebSockets. Action Cable allows you to create channels that handle bidirectional communication between the server and clients. Channels can be used for features like chat systems, live updates, or real-time notifications. Channel filenames end with _channel.rb, such as chat_channel.rb.

Customizing the Directory Structure

The default directory structure in Rails offers a strong framework for organizing the code of your application. To meet the unique needs of your project, you might, however, need to modify the structure in certain cases. You may modify the directory structure in Rails using a few ways:

1. Customizing Existing Directories:
   You can customize the existing directories within the Rails application to better suit your needs. For example, let's say you want to rename the default app/controllers directory to app/handlers:

   • Rename the directory:

   • Update the application configuration file (config/application.rb) to reflect the changes:

2. Adding Custom Directories:
   You can add custom directories to the Rails application to organize your code in a way that makes sense for your project. For example, let's say you want to add a services directory to hold your service objects:

   • Create a new directory:

   • Update the application configuration file (config/application.rb) to include the new directory:

   • Place your service objects in the new directory (app/services) and define them as regular Ruby classes.

3. Using Namespaced Directories:
   Namespacing is a way of organizing code hierarchically to avoid naming conflicts and it involves grouping related classes, modules, or other code entities under a common namespace. Rails support namespacing your application's code by using directories with corresponding modules or classes. Let's say you want to create an "admin" namespace for your controllers:

   • Create a new directory and module:

   • Define a namespaced controller within the new directory:

   • Define the route for the namespaced controller in config/routes.rb:

   This will create routes like /admin/users that map to the Admin::UsersController in the namespaced directory.

These are just a few examples of how you can customize the directory structure in a Rails application. The approach you choose depends on the specific needs of your project.