Ruby on Rails Interview Questions for Fresher

1. What is Ruby on Rails?

Ruby on Rails is an open-source, server-side web application development framework that is written in the Ruby programming language.

• Open-source: Anyone can use and contribute to Ruby on Rails, making it a collaborative and constantly evolving framework.
• Server-side: Ruby on Rails handles tasks happening behind the scenes on a web server, like processing data and interacting with databases.
• Web application development: Ruby on Rails streamlines the process of creating websites and web apps with features like user accounts, databases, and dynamic content.

2. What is the naming convention in Ruby on Rails?

• Database table: Plural with underscores separating words (e.g., book_clubs).
• Model Class: Singural with the first letter of each word capitalized (e.g., BookClub).
• Variables: All letters are lowercase, and words are separated by underscore (e.g., book_club)
• Controller: Represented in plural form like OrdersController.
• Class and Module: Class and Module names should also be written in CamelCase, no underscore (e.g., UserManager)

3. Explain ORM in Ruby on Rails?

In Rails, the ORM or Object Relationship Model indicates that your classes are mapped to the database table, and objects are directly mapped to the table rows. The attributes and relationships of objects in an application may be easily stored and retrieved from a database using ORM, which requires less overall database access code and does not require writing SQL queries directly.

4. What is the difference between false and nil in Ruby on Rails?

5. What is the difference between String and Symbol?

6. Explain the role of the sub-directory app/controller and app/helper.

• app/controllers: All the controller files are stored here. A controller handles all the web requests from the user.
• app/helper: The helper’s 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. 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

7. What is Active Record in Ruby on Rails?

• Active record is an Object-Relational Mapping framework in Ruby on Rails.
• It simplifies database interaction by mapping database tables to ruby classes
• Active Record facilitates Create, Read, Update, and Delete operations without writing raw SQL queries.
• Developers can define associations between models and enforce data validation easily.
• It provides callbacks for executing logic at specific points in the object lifecycle, enhancing flexibility in application development.

8. What is Rails Migration?

A Rails migration is a tool for altering the database schema of an application. Instead of handling SQL scripts, you use a domain-specific language to define database modifications (DSL). Because the code is database-agnostic, you can quickly port your project to a different platform. Migrations can be rolled back and managed alongside your application source code

9. List out what can Rails Migration do.

Here are the functions of rails migration:

• Manage changes to the database schema.
• Create, modify, or delete tables, columns, and indexes.
• Version control with timestamped files.
• Abstract away database-specific SQL.
• Support rollback operations for reverting changes.
• Initialize database schema for consistency across environments.

10. What is Mixin in Rails?

Mixin in ruby allows modules to access instance methods of another one using the include method. Mixin provides a controlled way of adding functionality to classes. The code in the mixin starts to interact with the code in the class. In ruby, a code wrapped up in a module is called mixins that a class can include or extend. A class consists of many mixins.

11. How to define the Instance variable, Global variable, and Class variable in Ruby.

• Ruby Instance variable begins with “@”
• Ruby Class variables begin with “@@”
• Ruby Global variables begin with “$”

12. How many types of Association relationships does a Model have?

There are three different types of association relationships in Ruby on Rails:

• One-to-One Association Relationships
• One-to-Many Association Relationships
• Many-to-Many Association Relationships

13. What is Rails Scaffolding?

Scaffolding in Rails is a way to generate a basic structure for your application, including the necessary files and code to perform CRUD (Create, Read, Update, and Delete) operations.

• It’s like a blueprint for your application, providing a starting point and a guide for how to organize your code.
• Scaffolding is an extremely useful feature that creates a basic structure of the application including controllers, routes, views, and models.
• It speeds up the development process by encouraging best practices and providing a consistent structure.

14. Name the three default environments in Rails.

In Ruby on Rails, the three default environments are:

1. Development: This environment is used by developers for building and testing the application locally. It typically has settings optimized for ease of development and debugging.
2. Test: The test environment is used for running automated tests, such as unit tests, integration tests, and system tests. It’s separate from the development environment to ensure that tests don’t interface with the development process and vice versa.
3. Production: This environment is where the application runs in a live, production environment, serving real users. It’s optimized for performance, reliability, and security.

15. What are the three components of Ruby on Rails?

The three primary components of Ruby on Rails are:

1. Model:

• Responsible for managing the data and business logic of the application.
• Interacts with the database to perform CRUD (Create, Read, Update, Delete) operations on data.
• Represents the underlying structure and rules of the application’s data domain.
• Often implemented using ActiveRecord, Rails’ Object-Relational Mapping (ORM) library.

2. View:

• Handles the presentation layer of the application.
• Responsible for generating the user interface and displaying data to users.
• Typically consists of HTML templates with embedded Ruby code (ERB) or other templating engines.
• Separation of concerns principle: Views should focus solely on displaying information and not contain business logic.

3. Controller:

• Acts as an intermediary between the model and the view.
• Receives requests from the user’s browser, processes them, and determines the appropriate response.
• Orchestrates the flow of data and operations between the model and the view.
• Implements application logic, such as authentication, authorization, and data validation.
• Typically consists of action methods that correspond to different HTTP request types (e.g., GET, POST, PUT, DELETE).

16. What is Gemfile in Ruby on Rails?

In Ruby projects, a Gemfile is a file that contains the list of Gem dependencies of the project. The Gemfile should be present at the root of the project. You can specify your list of gems with their version number.

17. What is MVC and How it Works?

MVC, or Model-View-Controller, is a software design pattern commonly used in web development frameworks like Ruby on Rails. It divides the application into three interconnected components, each with its responsibilities:

1. Model: The Model represents the data and the business logic of the application. It interacts with the database to retrieve, store, and manipulate data. In Ruby on Rails, models are typically ActiveRecord classes that correspond to database tables. They encapsulate data validation, associations, and other logic related to data manipulation.
2. View: The View is responsible for presenting data to the user in a readable format. It generates HTML, CSS, and JavaScript code that is sent to the user’s web browser. Views in Ruby on Rails are often written using embedded Ruby (ERB) templates, which allow Ruby code to be embedded within HTML markup. Views render data provided by the controller and often include dynamic content based on user input or application state.
3. Controller: The Controller is an intermediary between the Model and the View. It receives requests from the user’s browser, interacts with the Model to retrieve or update data, and determines which View to render in response to the request. Controllers in Ruby on Rails are Ruby classes that inherit from the ApplicationController class and define action methods corresponding to different HTTP requests (e.g., GET, POST, PUT, DELETE). Each action method typically performs some business logic, retrieves data from the Model, and renders a corresponding View.

18. What is the Garbage Collection in Ruby on Rails?

Garbage collection is a technique for controlling the amount of memory computer programs use. Garbage collection and other memory management techniques, like reference counting, work by having the language keep track of which objects are used by a program rather than the developer.

• This allows the programmer to concentrate on the business logic or other challenges at hand rather than the intricacies of memory allocation and release.
• This also aids program stability and security, as improper memory management can cause crashes, and memory management bugs account for a major fraction of security bugs.

19. What is Class Library in Ruby?

Ruby class libraries consist of a variety of domains, such as thread programming, data types, various domains, etc. These classes give flexible capabilities at a high level of abstraction, giving you the ability to create powerful Ruby scripts useful in a variety of problem domains. The following domains that have relevant class libraries are,

• GUI programming
• Network programming
• CGI Programming
• Text processing

20. What is your understanding of the DRY code?

DRY, which stands for ‘don’t repeat yourself,’ is a principle of software development that aims at reducing the repetition of patterns and code duplication in favor of abstractions and avoiding redundancy.

21. What are the benefits of using Ruby on Rails?

Some Benefits of using Rails on Rails in 2024 is:

• Rapid Development: Ruby on Rails enables fast development thanks to its convention over configuration principle, reducing setup time and allowing developers to focus on coding.
• Developer Productivity: Ruby’s clean syntax and extensive library of gems streamline development tasks, enhancing developer efficiency and speeding up project completion.
• Modular Design: Rails encourages modular architecture, facilitating code organization, maintenance, and scalability as projects evolve.
• Active Community: With a vibrant community of developers, Rails benefits from continuous support, updates, and contributions, ensuring its relevance and reliability.
• Security Features: Rails comes with built-in security mechanisms, protecting applications from common vulnerabilities such as SQL injection and cross-site scripting (XSS).
• Scalability: While initially favored for its rapid development capabilities, Rails can also scale effectively to handle increased traffic and data volume as applications grow.
• Cost-Effectiveness: Being open-source, Ruby on Rails eliminates licensing fees, making it an economical choice for startups and businesses seeking to develop robust web applications without significant financial investment.

22. What is Nested Layout in Ruby on Rails?

Nested layouts are used when you want to create a hierarchy of layouts, where one layout file wraps another layout file. This can be useful when you have common elements shared across multiple pages, but some pages have additional layout requirements.

1. To use nested layouts in Rails, you first create your layout files in the app/views/layouts directory.
2. Let’s say you have two layout files: application.html.erb and admin.html.erb.
3. You want the admin.html.erb layout to inherit from the application.html.erb layout.

23. What is the Role of Load and Require in Ruby?

• load(): We use load to execute code.
• require(): We use require to import libraries.

24. Explain what Delete does in Ruby on Rails.

The delete method is used to remove records from the database. Unlike the destroy method, which triggers callbacks and validations, delete directly removes records without any additional processing, making it faster but bypassing these mechanisms.

For example, suppose we have a User model and want to delete a specific user with an ID of 1:

user = User.find(1)user.delete

This code will delete the user with an ID of 1 from the database immediately. Alternatively, if we want to delete all users with a certain condition, such as users with the age of 30:

User.where(age: 30).delete_all

This command will remove all users whose age is 30 from the database in a single operation.

25. How do you create comments in Ruby code?

# symbol followed by your comment text is used for adding comments in Ruby on Rails. Comments are ignored by the Ruby interpreter but help document your code. (Single line comment).

26. What is the difference between single quotes and double quotes for strings

Both can be used for strings, but double quotes allow string interpolation (embedding variables within the string using #{})

Ruby on Rails, often shortened to Rails, is a server-side web application framework written in Ruby under the MIT License. Rails is known for its ease of use and ability to build complex web applications quickly. It was created by David Heinemeier Hansson and was first released in 2004. Now, Over 3.8 million websites currently use Ruby on Rails, with over 600,000 active sites. This translates to roughly 5.3% of all websites being built with Rails.

Here, we provided over 50+ Ruby on Rails Interview Questions and Answers tailored for both beginners as well as for experienced professionals with 2, 7, or up to 10 years of experience. Here, we cover everything about Ruby on Rails from basic concepts to advanced concepts such as Core Syntax, OOPs concepts, Model-View-Controller (MVC) architecture, Active Record, CoC Principle, Routing, Authentication and authorization, API development, Security, Deployment, Caching, etc., and more that help you to crack your next Rails interview.