Understanding the Rails Directory Structure

When starting to learn Ruby on Rails, one of the first things you will come across is its directory structure. Understanding the Rails directory structure is crucial as it helps you organize your code, assets, and configurations efficiently. In this article, we will dive into each directory and explore its purpose and significance in a typical Rails application.

1. The app Directory

The app directory is where the majority of your Rails application code resides. It is further divided into several subdirectories, each serving a specific purpose:

a. Models

The app/models directory holds the model classes of your Rails application. Models represent the data and logic of your application and are responsible for interacting with the database. Each model class typically corresponds to a database table and inherits from ActiveRecord::Base.

b. Views

Rails uses a templating system called Action View to generate the dynamic web pages. The app/views directory contains the view templates rendered by your controllers. Views generally consist of HTML mixed with embedded Ruby code, allowing you to present data fetched from your models.

c. Controllers

The app/controllers directory contains the controller classes that handle requests and responses from the webserver. Controllers act as intermediaries between models and views, making decisions based on incoming requests and fetching or updating data in the models accordingly.

d. Helpers

Helpers provide utility methods that can be used within views, controllers, or models. The app/helpers directory contains modules with methods that can be shared across multiple parts of your application, reducing code duplication. Rails automatically includes these methods in the appropriate context.

e. Mailers

Rails makes it easy to send emails from your application. The app/mailers directory is where you define mailer classes responsible for composing and delivering emails. Mailers can use view templates, similar to controllers, to generate the email content.

f. Jobs

The app/jobs directory holds your background job classes if you are using a job processing library like Sidekiq or Delayed Job. Background jobs help you offload time-consuming tasks from the main request-response cycle to improve performance and user experience.

2. The config Directory

The config directory contains various configuration files essential for your Rails application.

a. Database

The config/database.yml file holds the database configuration for different environments like development, test, and production. It specifies the database adapter, connection details, and other settings required to establish a connection with your chosen database.

b. Environment

The config/environment.rb file is the entry point for your Rails application. It loads the entire application framework and sets up the environment-specific settings.

c. Routes

The config/routes.rb file is where you define the routes for your application. Routes determine how incoming HTTP requests are mapped to controller actions. You can define RESTful resources, custom routes, and route constraints in this file.

d. Initializers

The config/initializers directory contains various initializer scripts that run when your application boots up. Initializers are used to configure gems, set up constants, or perform any other required setup code.

e. Locales

If your application needs to support multiple languages, you can store the translation files in the config/locales directory. Rails uses the I18n module to handle internationalization and localization.

3. The public Directory

The public directory is where static assets like images, stylesheets, and JavaScript files are stored. It is directly accessible by web browsers, so you can reference these assets using simple URLs. However, it is recommended to use the Rails asset pipeline for managing and serving static assets.


Understanding the Rails directory structure is fundamental to building Rails applications efficiently. Each directory has its specific purpose and plays a vital role in the overall architecture of your application. With a proper grasp of the directory structure, you can organize your code and assets effectively, making your Rails development experience much smoother.

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