Top 50+ Ruby on Rails Interview Questions and Answers

150

Preparing for a Ruby on Rails interview can feel challenging – especially with the popularity of this powerful web development framework. Ruby on Rails powers over 1 million websites globally – used by big names like GitHub, Shopify, and Airbnb. As more companies adopt Rails for building powerful web applications – the demand for skilled developers has grown. This guide brings together the top 50+ Ruby on Rails interview questions and answers to help you prepare confidently. 

These questions cover the essential topics interviewers are likely to ask – so you can showcase your skills and land the job.

Ruby on Rails Basic Interview Questions

Here are some common and basic Ruby on Rails interview questions and answers. 

1. What is Ruby on Rails?

Ruby on Rails, often called Rails – is a web application framework built on the Ruby programming language. It follows the MVC (Model-View-Controller) architecture and provides tools to quickly build database-backed applications. Rails is known for its convention-over-configuration approach – which makes development faster by setting sensible defaults.

2. What is MVC in Ruby on Rails?

This is one of the most basic Ruby interview questions. 

MVC stands for Model-View-Controller – an architectural pattern that separates application logic:

• Model: Manages data and business logic.
• View: Displays data to the user (the user interface).
• Controller: Handles user input and interacts with the model and view. This separation helps keep code organized and easy to maintain.

3. What are Gems in Ruby on Rails?

Gems are libraries or packages that add specific functionalities to a Rails application. They can be easily installed and used to extend the features of Rails. For example, Devise is a gem used for authentication, and Active Record is a gem that helps interact with databases.

4. What is Active Record in Rails?

Active Record is Rails’ Object-Relational Mapping (ORM) layer. It allows developers to interact with databases using Ruby objects instead of writing SQL queries. Each class in Active Record represents a table in the database, and each instance represents a row.

5. What is the purpose of migrations in Rails?

Migrations are a feature in Rails that allow developers to change the database schema over time in a consistent and easy way. They let you add, remove, or modify tables and columns in the database – and they help keep track of these changes across different environments (like development and production).

Ruby on Rails Interview Questions for Freshers

Let’s take a look at some commonly-asked Ruby on Rails interview questions and answers for freshers. 

6. What is the difference between nil, false, and empty in Ruby?

nil represents the absence of value, false is a Boolean value, and empty checks if a container (like a string or array) has no elements. Only false and nil are considered falsy in Ruby.

7. What is a Rails controller?

It is one of the most common Ruby and Rails interview questions for freshers. 

A Rails controller is responsible for handling user requests, retrieving data from models, and passing it to views. It connects the user interface with the application’s logic and acts as an intermediary.

8. Explain the role of routing in Rails.

Routing in Rails directs user requests to the appropriate controller actions. It defines URL patterns and determines which action should be invoked based on the URL – making the application structure more organized.

9. What are filters in Rails?

Filters in Rails are methods that run before, after, or around controller actions. Common filters like before_action help set up variables, authentication, or any other setup required before the main action runs.

10. What is CRUD in the context of Rails?

CRUD stands for Create, Read, Update, and Delete – the basic operations you can perform on data. Rails applications often provide CRUD functionalities to manage resources within the database.

Ruby on Rails Interview Questions for Experienced

These are some important RoR interview questions and answers for experienced candidates. We’ve organized them based on years of experience.

Ruby on Rails Interview Questions for 2 Years Experienced Candidates 

Here are the common RoR interview questions for experienced developers. 

11. What is a concern in Rails?

Concerns are modules that allow you to organize reusable code in Rails. They help split functionality across files and are commonly used for shared logic between models or controllers.

12. What is eager loading in Rails?

Eager loading is a way to load related objects with a single query, reducing N+1 query issues. It’s often done with .includes to improve database performance.

Ruby on Rails Interview Questions for 3 Years Experienced Candidates 

These are some important Ruby on Rails experience interview questions and their answers. 

13. What is a Polymorphic Association?

Polymorphic associations allow a model to belong to more than one other model using a single association. For example, a Comment model can belong to both Post and User.

14. How do you handle background jobs in Rails?

Background jobs in Rails can be managed with tools like Sidekiq or Delayed Job. They allow tasks to be processed asynchronously, improving response times.

Ruby on Rails Interview Questions for 4 Years Experienced Candidates

Take a look at these Ruby interview questions for experienced candidates. 

15. What is a Service Object, and when do you use it?

Service objects handle complex business logic, separating it from controllers and models. They improve code organization and are helpful for reusing logic across the app.

16. Explain Action Cable in Rails.

Action Cable is Rails’ WebSocket framework, enabling real-time features like live chat. It allows servers to push updates to clients instantly.

Ruby on Rails Interview Questions for 5 Years Experienced Candidates 

Here are some interview questions Ruby on Rails for people with around 5 years of experience. 

17. What are custom validations, and how do you create them?

Custom validations let you define specific rules for data. They’re created using validate in models and are useful when standard validations don’t cover certain requirements.

18. What is STS (Strict Transport Security) in Rails?

STS is a security policy that forces browsers to communicate only over HTTPS. Rails supports it through config.force_ssl, adding an extra layer of security.

Ruby on Rails Interview Questions for 7 Years Experienced Candidates 

If you have 7 years of experience – prepare with these Ruby and Rails interview questions. 

19. What are Strong Parameters?

Strong Parameters help filter incoming request parameters – enhancing security by allowing only permitted attributes for mass assignment. This approach prevents unwanted changes to data.

20. Explain the Decorator Pattern in Rails.

Decorators add custom behavior to models without modifying them directly. In Rails, decorators are often used to format data or add presentation logic.

Ruby on Rails Interview Questions for 8 Years Experienced Candidates 

Here are some important Ruby interview questions and answers for candidates with 8 years of experience. 

21. What is Duck Typing in Ruby?

Duck Typing in Ruby means an object’s methods determine its behavior rather than its class. As long as an object responds to a required method, it can be used in place of another.

22. Explain the Observer Pattern and its use.

Observers allow objects to watch for and respond to changes in other objects. In Rails, they are useful for separating responsibilities, such as handling notifications.

Ruby on Rails Interview Questions for 10 Years Experienced Candidates 

These are some commonly-asked senior Ruby on Rails developer interview questions and their answers. 

23. Explain Microservices and how Rails can be part of it.

Microservices are an architectural style dividing applications into small services. Rails can serve as a microservice, focusing on a specific function within a larger system.

24. How do you handle API versioning in Rails?

Rails manages API versioning by defining different versions in routes. It also uses namespaces in controllers to guarantee backward compatibility as APIs evolve.

Ruby on Rails Advanced Interview Questions

Here are some advanced senior Ruby on Rails interview questions and their answers. 

25. What is Sharding, and how can it be implemented in Rails?

Sharding divides a database into smaller, faster, manageable parts called shards. In Rails, it can be managed by configuring multiple database connections in database.yml and defining models to interact with specific shards. This optimizes data access for large datasets.

26. How does Rails handle Concurrent Requests, and what challenges does it face?

Rails handles concurrent requests using multi-threading or multi-processing servers like Puma. However, concurrency can introduce challenges such as race conditions and shared resource conflicts. These issues require careful management of memory and thread safety, particularly for database transactions and caching.

27. What is Dependency Injection, and how do you achieve it in Rails?

Dependency Injection is a design pattern for decoupling components by passing dependencies rather than hardcoding them. In Rails, it can be implemented using initializer files, service objects, or dependency injection libraries – promoting flexibility and easier testing.

Ruby on Rails Technical Interview Questions

Take a look at these common Ruby technical interview questions and their answers. 

28. How do you create a custom rake task in Rails?

You may also come across technical Ruby questions for interview like this one. 

Custom rake tasks are created by defining a new file in the lib/tasks directory. You define the task using the task method and write the task logic inside – which can be executed via the command line.

29. What are Scaffolds in Rails?

Scaffolds in Rails are a quick way to generate standard code for a resource, including models, views, and controllers. They help speed up development by providing a basic structure for CRUD operations without manual setup.

30. What is the purpose of rails db:migrate?

The rails db:migrate command applies database migrations – updating the database schema to match the defined structure in migration files. It ensures that the database remains in sync with the application code changes.

Ruby on Rails Developer Interview Questions

Here are some common Ruby developer interview questions and their answers. 

31. What is the purpose of the Gemfile in a Rails application?

The Gemfile specifies the gems (libraries) required by the application. It allows you to manage dependencies easily – guaranteeing that all necessary libraries are installed with the correct versions when running bundle install.

32. What does the rails console do?

The rails console provides an interactive shell for your Rails application – allowing you to run Ruby code, test models, and interact with the database directly. It’s useful for debugging and exploring application behavior.

33. What is the asset pipeline in Rails?

The asset pipeline is a framework in Rails for managing and serving web assets like JavaScript, CSS, and images. It combines, minifies, and compresses assets to optimize loading times, enhancing overall application performance.

Ruby on Rails Senior Developer Interview Questions

These are some important senior Ruby developer interview questions and their answers. 

34. What are Rails Environments, and how do they work?

This is one of the most commonly-asked senior Ruby interview questions. 

Rails environments (development, test, production) allow you to configure settings for different stages of the application lifecycle. Each environment has its own configurations – enabling tailored logging, error handling, and database settings to optimize performance and development workflows.

35. How do you handle exceptions and errors in Rails?

You can also expect such Ruby programming questions in your interview. Here’s how to answer it. 

Rails handles exceptions using rescue_from in controllers to catch errors. Custom error pages can be created, and the ApplicationController can be configured to log errors or send notifications for critical failures, enhancing application reliability.

36. What is Rails middleware, and how does it work?

Middleware components sit between the web server and the Rails application. They process requests and responses, allowing for functionalities like logging, session management, and authentication. This enables a cleaner separation of concerns within the application.

Ruby on Rails Coding Interview Questions

Here are some important Ruby on Rails coding questions and their answers. 

37. How would you create a simple model in Rails?

To create a simple model, use the command:

rails generate model ModelName attribute1:data_type attribute2:data_type

38. How do you validate a model’s presence in Rails?

To validate a model’s presence, use the following line in the model:

validates :attribute_name, presence: true

39. Create a Rails controller action to find a User by their email address and render their profile. If the user is not found, render a 404 error.

Here’s how you should answer such Ruby coding interview questions. 

class UsersController < ApplicationController

  def show_by_email

    @user = User.find_by(email: params[:email])

    if @user

      render json: @user

    else

      render status: :not_found

    end

  end

end

40. Write a method in a Rails model that returns the number of comments for a post. Assume the Post model has a has_many :comments association.

class Post < ApplicationRecord

  has_many :comments

  def comment_count

    comments.count

  end

end

Ruby on Rails Programming Interview Questions

Here are some important Ruby programming interview questions and answers. 

41. What are blocks in Ruby, and how are they used?

Blocks are chunks of code enclosed within do…end or curly braces {} that can be passed to methods. They allow for iteration and defining custom behavior. Additionally, blocks encapsulate functionality without the need to define a full method, enhancing code reusability.

42. What is metaprogramming in Ruby, and can you give an example of its use?

This is one of the most important Ruby metaprogramming interview questions. 

Metaprogramming allows Ruby code to alter its own structure at runtime. For example, define_method creates methods dynamically:

class DynamicMethod

  define_method(:greet) { "Hello!" }

end

This defines a greet method dynamically.

43. What is monkey patching in Ruby?

You may also come across Ruby programming interview questions like this one. 

Monkey patching is a technique to add or modify methods of existing classes or modules at runtime. While powerful, it can lead to conflicts and unexpected behavior if not used carefully. For example:

class String

  def shout

    self.upcase + "!"

  end

end

This adds a shout method to the String class.

Ruby on Rails Interview Exercises

Here are some Ruby programs for interview to help you prepare and land your dream job. 

44. Given an array, write a method that returns an array of duplicate values.

def find_duplicates(arr)

  arr.select { |e| arr.count(e) > 1 }.uniq

end

# Example usage:

puts find_duplicates([1, 2, 3, 1, 2, 4]).inspect  # Output: [1, 2]

45. Create a model called User with validations for name (presence) and email (format).

class User < ApplicationRecord

  validates :name, presence: true

  validates :email, format: { with: URI::MailTo::EMAIL_REGEXP }

end

46. Implement a method that reverses a given string without using built-in methods.

def reverse_string(str)

  reversed = ''

  str.each_char { |char| reversed = char + reversed }

  reversed

end

# Example usage:

puts reverse_string(“hello”)  # Output: “olleh”

Ruby Viva Questions

Here are some common Ruby on Rails questions and answers for viva preparation. 

47. What is the Rails convention over configuration principle?

The “convention over configuration” principle means that Rails provides defaults for many aspects of development, reducing the need for configuration. Developers can follow established conventions to save time, as Rails will automatically handle common tasks based on naming and structure.

48. How does Rails support testing, and what testing frameworks are commonly used?

Rails supports testing through built-in testing frameworks like Minitest and RSpec. It provides tools for unit testing, functional testing, and integration testing, allowing developers to write tests for models, controllers, and views, ensuring code quality and reliability.

Bloomberg Ruby on Rails Interview Questions

These are some important Ruby on Rails questions you may come across in Bloomberg interview. 

49. How can you optimize database queries in a Rails application?

“To optimize database queries in Rails, I use eager loading with includes to prevent N+1 problems, apply database indexes for faster searches, and write custom SQL for performance-critical tasks. I also analyze query plans with tools like EXPLAIN to identify any bottlenecks.”

50. How do you handle real-time data processing in a Ruby on Rails application?

“In a Ruby on Rails application, I handle real-time data processing using Action Cable to establish WebSocket connections for pushing updates to clients. I also use background jobs, like Sidekiq, to manage incoming data streams efficiently. Additionally, I integrate with external APIs or message brokers, such as Kafka, to ensure smooth data handling and timely updates.”

TCS Ruby on Rails Interview Questions

Here are some common Ruby interview questions and answers to help you prepare for your TCS interview. 

51. How do you implement security measures in a Ruby on Rails application?

“In Rails, I implement security by using strong parameters to prevent mass assignment, enabling CSRF protection by default, and validating user input to avoid SQL injection. I also use the has_secure_password method for secure password management and tools like Brakeman to identify code vulnerabilities.”

52. Can you describe a project where you implemented Ruby on Rails to solve a business problem?

“In a previous project, I developed a Ruby on Rails application to streamline the client onboarding process. By automating form submissions and integrating a document management system, we reduced onboarding time by 40% and improved client satisfaction through enhanced tracking and communication features.”

Wrapping Up

These are the 50+ Ruby on Rails interview questions that can help you prepare for your next interview. Understanding these questions will improve your chances of success. And hey, if you’re looking to take the next step in your career – visit Hirist to find the best Ruby on Rails jobs in India. This IT job portal connects you with exciting opportunities tailored to your expertise.