The 3 Core Concepts of Ruby on Rails
A beginner-friendly introduction to the core concepts of Ruby on Rails, focusing on the file structure, scaffold functionality, and database migrations.
Published Nov 8, 2025 by Malachi Rails
Key Insights
Ruby on Rails has a structured file system where the app folder contains most of the important components (controllers, views, and models)
The config folder, especially the routes.rb file, is crucial for defining user actions and their corresponding file paths
Scaffolding is a powerful feature that automatically generates CRUD (Create, Read, Update, Destroy) functionality for a model
Migrations provide a systematic way to modify the database schema over time
The MVC (Model-View-Controller) pattern is central to Rails architecture, separating data logic, user interface, and control flow
Rails follows convention over configuration, making development faster by reducing the need for explicit configuration
0:00
Introduction and Rails App Generation
“I'm going to be introducing you to the core concepts of Ruby on Rails. So, we're going to take a look at the main things you need to know. This video is directed directly towards beginners who haven't really used the framework before.”
The video begins with the instructor explaining that he's creating this tutorial specifically for beginners who are new to Ruby on Rails. He demonstrates how to generate a new Rails application using the rails new command, explaining that this command can be modified to specify database types and other configuration options.
After generating the application, he shows the basic file structure created by Rails. This section establishes the foundation for understanding how a Rails application is organized before diving into more specific concepts.
Takeaways
Rails applications can be quickly generated using the 'rails new' command
The command can be customized to specify database types and other features like CSS frameworks
The initial generation creates a complete file structure with everything needed to start building
This process demonstrates Rails' philosophy of 'convention over configuration'
1:30
Understanding the Rails File Structure
“The most important one to understand is this folder called the app folder. This is where most of the work actually happens.”
The instructor provides a detailed overview of the key folders in a Rails application, focusing on the app folder which contains controllers, views, and models. He explains that controllers handle server-side logic, views contain HTML.ERB files that are served to users, and models communicate with the database.
He also highlights the importance of the config folder, particularly the routes.rb file which defines how user actions map to controller actions. This section establishes a clear understanding of Rails' MVC (Model-View-Controller) architecture and file organization.
Takeaways
The app folder is the heart of a Rails application, containing controllers (server logic), views (UI), and models (database communication)
The config folder contains crucial configuration files, with routes.rb being particularly important
Rails follows the MVC (Model-View-Controller) pattern for organizing code
Models represent data structures with attributes (like 'email' or 'name')
Understanding file structure is fundamental to working effectively with Rails
3:09
Scaffolding and CRUD Functionality
“Rails scaffold is like one of the most powerful features of this beautiful framework... essentially a scaffold is something that creates a CRUD functionality in your application.”
The instructor demonstrates one of Rails' most powerful features: scaffolding. Using the command rails g scaffold post title description, he generates a complete set of files for managing a 'post' resource with title and description attributes.
He explains that CRUD stands for Create, Read, Update, and Destroy - the four basic functions of persistent storage. After running the migration with rails db migrate, he shows how the scaffold has automatically created a full interface for managing posts, complete with forms for creation and editing, and views for listing and showing individual posts.
Takeaways
Scaffolding quickly generates all the code needed for CRUD operations on a resource
CRUD (Create, Read, Update, Destroy) is a fundamental concept in web applications
The scaffold command creates the model, controller, views, and database migration in one step
The generated code follows Rails conventions and best practices
Using scaffolds can significantly speed up development for standard data operations
7:29
Database Migrations
“Migrations in Ruby on Rails is a way to change the schema.rb. The schema.rb is the structure of the database, the representation of the database.”
In the final section, the instructor introduces the concept of migrations, which allow developers to modify the database schema over time. He demonstrates creating a migration to add an email field to the posts table using the command rails g migration add_email_to_posts email:string.
He explains the naming convention for migrations and how Rails interprets this to automatically generate the appropriate code. After running rails db migrate, he shows how the schema.rb file is updated to reflect the new column, illustrating how migrations provide a systematic and version-controlled way to evolve the database structure.
Takeaways
Migrations provide a way to modify database schema in a structured, version-controlled manner
The naming convention of migrations is important as it influences the automatically generated code
Running migrations updates the schema.rb file, which represents the current database structure
Migrations make it easy to track and apply database changes across different environments
Conclusion
Ruby on Rails stands out as a framework that emphasizes developer productivity through its three core concepts: structured file organization with MVC architecture, powerful scaffolding for rapid CRUD development, and a robust migration system for database management. These concepts work together to make Rails an excellent choice for beginners and experienced developers alike.
By understanding these fundamentals, developers can leverage Rails' 'convention over configuration' philosophy to build web applications quickly and efficiently. For beginners looking to enter web development, mastering these core Rails concepts provides a solid foundation that makes learning other frameworks easier. Whether you're building a personal project or an enterprise application, these principles will guide your development process and help you create maintainable, well-structured code.