Top 50 Ruby on Rails Interview Questions and Answers (2024)

Introduction

Ruby on Rails, commonly known as Rails, is a powerful and popular web application framework built on the Ruby programming language. It follows the Model-View-Controller (MVC) architecture, making it easy to build, manage, and scale web applications. Rails is favored for its simplicity, convention over configuration approach, and rapid development capabilities. As companies continue to adopt Ruby on Rails for building robust and scalable applications, demand for skilled Rails developers remains high.

In this blog, we will discuss the Ruby On Rails Interview Questions.

What is Ruby on Rails?

Ruby on Rails is used to create online apps and services across many industries. It's a popular web framework for new businesses because of its simplicity, which allows for rapid application development with a limited number of teams. Do you want to work on Ruby on Rails? If yes, then you are on the right road. We will divide the question into three difficulty levels easy, medium, and hard. This blog will teach Ruby On Rails Interview Questions, what to anticipate and how to conquer the next interview.

Ruby on Rails Interview Questions for Freshers

The interviewer will start by asking easy-level Ruby on rails interview questions, and you need to answer them quickly with valid points. Below are some easy questions that will help you in your interview.

1. What are the functions of the subdirectories app/controllers and app/helpers?

The app/controllers aid Rails in finding controller classes and effectively handles a user web request; the helper stores any helper classes that assist the controller, model, and view classes.

2. What exactly is Ruby on Rails?

Ruby on Rails is a web application framework that is open source. It is written in the Ruby language and aids in the creation of numerous apps.

3. Give five examples of what Rails Migration can achieve.

Rails Migration allows you to rename a table, add a column, change a column, drop a table, remove a column, and many other things.

4. What command can you use to make a topic controller?

We can use this command to make a topic controller.

C:\ruby\library> ruby script/generate controller subject

5. What exactly is the Rails Controller?

Rails Controller is the heart of your application, facilitating overall user, view, and model interaction. It's also noted for properly managing URLs and controlling auxiliary modules and sessions.

6. What is the purpose of trash collection in Ruby on Rails?

Garbage collection serves several functions, including deleting pointer values and removing objects from memory that is not accessible, among others. In short, garbage collection aids in the release of memory for other processes.

7. How can Rails be protected from Cross-Site Request Forgery?

To guard against Cross-Site Request Forgery attempts by hackers, add "protect from forgery" in your ApplicationController.

8. What are some of the benefits of utilizing Ruby on Rails?

Ruby on Rails offers several benefits. It increases the productivity of a programmer's job. It's also entirely open-source and free. Furthermore, it enables programmers to construct code that operates on actual code rather than data.

9. Name three Ruby on Rails limitations.

Ruby on Rails lacks many functionalities, making it unsuitable for some programmers. This includes linking to several databases at the same time, connecting to multiple database servers at the same time, and using foreign keys in databases.

10. Who is the developer of Ruby on Rails?

David Heinemeier Hansson is the programmer who developed the famous Ruby on Rails web development framework. He is also a partner at Basecamp, a web-based software development startup.

11. Explain the difference between include and extend.

'extend' adds methods to the class but not to its instance, and 'include' adds methods solely to a class instance.

12. Explain the difference between Procs and Blocks.

The following differences are the primary vital points between procs and blocks. Block is just an element of a method's syntax, whereas proc contains block-like properties. Procs are objects, although blocks are not.

An argument list can only contain one block. Only block cannot be placed in a variable, although Proc can.

13. What exactly is interpolation in Ruby?

The technique of putting a string into a literal in Ruby is known as interpolation. A string can be interpolated into the literal using a Hash (#) within {}.

14. What is the definition of the defined operator in Ruby?

The defined operator indicates whether or not a passed expression is defined. If the expression is not defined, it returns null; otherwise, it returns the description string.

15. What are the different types of variables available in the Ruby class?

The primary four variables are the local variable, global variable, class variable, and instance variable.

16. Tell me how to declare a block in Ruby programming language.

The code in the block is always surrounded by the braces ({}). The "yield statement" is used to call a block.

17. What is the critical limitation of ruby on rails?

Ruby on Rails was developed to create a CRUD web application using MVC.

Ruby on Rails does not support the following features:
1. Databases with foreign keys
2. Linking to many databases at the same time
3. Web-based soap services
4. Connection to many database servers at the same time

18. Explain how you can execute a Rails application without having to create a database.

You may run your application by uncommenting the line in the environment.rb

path=> rootpath conf/environment.rb

config.frameworks = [ action_web_service, :action_mailer, :active_record]

19. What is explicitly Rails Migration?

Rails Migration allows Ruby to modify the database schema, allowing you to utilize a version control system to keep things synced with the actual code.

20. Tell me, what things can I do with ruby?

You may use Ruby the same way as any other general-purpose programming language. Web applications, servers, system utilities, database operations, backups, parsing, and even biology and medicine are a few examples.

Ruby on Rails Interview Questions for Experienced

The hard-level Ruby on rails interview questions carry more weightage. Answering them in an exemplary manner will dramatically increase your chances of selection. These questions are crucial and require a well-structured answer prepared in your mind before explaining the answer to your interviewer.

21. How do Rails implement Ajax?

Ajax-powered web pages retrieve new or altered web pages from the server instead of regular web pages, which need you to refresh the page to acquire the most up-to-date information.

Rails trigger the ajax operations by the following methods.

Some triggers fire: The trigger might be a user clicking on a link or button or changing the data in a field or on a form.

The web client contacts the server: A Java-script method, XMLHttpRequest, transfers data associated with the trigger to a server action handler. The information may be the ID of a checkbox, the entire form, or the text in the entry field.

The server processes: The server-side action handler processes the data and returns an HTML fragment to the web client.

The client-side JavaScript, which Rails create automatically, gets the HTML fragment and utilizes it to alter a specific area of the current page.

22. What exactly do you mean by scaffolding, and what benefits might Ruby provide in this regard?

Users are frequently required to create code early in project development. These codes aid in developing the application in a highly dependable and timely way, as well as close check on the operation of specific essential components. Scaffolding is done automatically in Ruby, and users are free to focus on core programming from the first day of work.

23. Create a Ruby function to determine whether a string is a palindrome.

def palindrome?(str)

str == str.reverse

End

24. What genuinely are strong parameters? Explain briefly.

Many Rails projects use Strong Parameters, also known as Strong Params, to improve the security of data submitted via forms. Developers can utilize strong parameters to regulate which parameters are accepted and used by the controller. Any unnecessary or possibly dangerous parameters will be disregarded and adequately filtered out by permitting just the anticipated parameters. This is especially important when utilizing Active Model bulk assignments because several parameters may be given simultaneously.

25. A model has how many different types of associations and relationships?

When you have several models in your rails application, you must make connections between them. You may accomplish these using affiliations. Active Record supports three different kinds of associations:

One-to-one: When one object possesses precisely one of another item, the connection is one-to-one.

One-to-many: When a single item may be a member of many other objects, this is referred to as a one-to-many connection. For example, one subject may contain several books.

Many-to-many: When the first item is connected to one or more of the second object, and the second object is related to one or many of the first object, a many-to-many connection occurs.

26. What is the distinction between Ruby on Rails observers and callbacks?\

In Rails, callback methods can only be called at particular points in an object's life cycle, such as validation, creation, updating, and deletion. Unlike rails observers, the rails callback is only active for a short period.

Rails observers are similar to callbacks in that they are used when a method is not directly tied to the life cycle of an object. It may be added or detached at any moment and has a longer lifespan.

27. What is the most attractive thing you've discovered about Ruby on Rail?

It strongly supports Metaprogramming, and, unlike other frameworks, all codes may be created rapidly and without regard for other sophisticated systems. In addition, big jobs may be completed quickly using this strategy, which is one of the most remarkable things about Ruby.

28. What is your specific knowledge about the Active Records Rail?

It is essentially a subset of Ruby, and the version is convenient for performing some essential duties in the database columns. The column may be reused for performing other vital duties.

29. How can you say that the ruby symbols differ from the variables?

Symbols are usually immutable, but Ruby's String is changeable. Symbols are more likely to string than simple variables. Users may keep pace with a single copy of the sign. At the same time, a single variable is insufficient for the users. Furthermore, users have the freedom to employ symbols against enums, which is not feasible with variables.

30. Tell me, how does Ruby on Rails function?

Rails is a web application framework that integrates the Ruby programming language like HTML, CSS, and JavaScript to produce a web application that runs on a web server. Rails is a server-side, or "back end," web application development platform since it operates on a web server (the web browser is the "front end").

Ruby on Rails Coding Interview Questions

31. How do you define a simple route in Rails that maps to a controller action?

# routes.rb
get 'welcome/index'

Output:
This route maps the URL /welcome/index to the index action in the WelcomeController.

32. How can you fetch all records from a User model in Rails?

# Controller
@users = User.all

Output:
This will fetch all the records from the users table.

33. How do you create a new record in the Post model in Rails?

# Controller
Post.create(title: 'First Post', content: 'This is my first post!')

Output:
This will create a new Post record with the given title and content.

34. How can you add a validation to ensure the presence of a field in a Rails model?

# user.rb (Model)
class User < ApplicationRecord
  validates :name, presence: true
end

Output:
This will validate that the name field must be present before saving a User record.

35. How do you define a one-to-many association between models in Rails?

# user.rb
class User < ApplicationRecord
  has_many :posts
end

# post.rb
class Post < ApplicationRecord
  belongs_to :user
end

Output:
This defines a one-to-many relationship where one User can have many Posts.

36. How can you update a record in Rails?

# Controller
user = User.find(1)
user.update(name: 'Updated Name')

Output:
This finds the User with ID 1 and updates its name to 'Updated Name'.

37. How can you implement a basic scope in a Rails model to fetch active records?

# user.rb
class User < ApplicationRecord
  scope :active, -> { where(active: true) }
end

Output:
You can now call User.active to get all users with active: true.

38. How do you add a foreign key to an existing table in Rails migration?

class AddUserIdToPosts < ActiveRecord::Migration[6.0]
  def change
    add_reference :posts, :user, foreign_key: true
  end
end

Output:
This migration adds a user_id column to the posts table and sets a foreign key relationship with the users table.

39. How can you render a partial in Rails?

<%= render 'shared/header' %>

Output:
This will render the partial _header.html.erb from the shared folder.

40. How do you redirect to another page after an action in Rails?

# Controller
def create
  @post = Post.new(post_params)
  if @post.save
    redirect_to @post
  else
    render 'new'
  end
end

Output:
If the post is successfully saved, it redirects to the show page of the newly created post. If not, it re-renders the new template.

Ruby on Rails MCQ Questions

1. Which architectural pattern does Ruby on Rails follow?

A) Model-View-Controller (MVC)
B) Model-View-Presenter (MVP)
C) Model-View-ViewModel (MVVM)
D) Microservices

Answer: A) Model-View-Controller (MVC)

2. What is the purpose of the rails console command?

A) To start the Rails server
B) To open an interactive Ruby session with your Rails application
C) To generate a new controller
D) To run database migrations

Answer: B) To open an interactive Ruby session with your Rails application

3. In Rails, which of the following is used to interact with the database?

A) ActiveJob
B) ActionCable
C) ActiveRecord
D) ActionMailer

Answer: C) ActiveRecord

4. Which Rails command is used to generate a new migration?

A) rails generate model
B) rails generate controller
C) rails generate migration
D) rails generate scaffold

Answer: C) rails generate migration

5. How do you define a relationship where one model belongs to another in Rails?

A) has_many
B) has_and_belongs_to_many
C) belongs_to
D) has_one

Answer: C) belongs_to

6. What does rake db:migrate do in a Rails application?

A) Creates a new database
B) Rolls back the database
C) Applies the migrations to update the database schema
D) Seeds the database with initial data

Answer: C) Applies the migrations to update the database schema

7. Which file is used to configure routes in a Rails application?

A) config/initializers/routes.rb
B) config/application.rb
C) config/routes.rb
D) config/database.yml

Answer: C) config/routes.rb

8. What does the rails db:seed command do?

A) Runs database migrations
B) Seeds the database with initial data
C) Deletes records from the database
D) Rolls back the last migration

Answer: B) Seeds the database with initial data

9. In Rails, what is a migration?

A) A database rollback
B) A modification of the database schema
C) An update to the Rails version
D) An HTTP request action

Answer: B) A modification of the database schema

10. What does rails new command do?

A) It starts the Rails server
B) It creates a new Rails application
C) It installs Rails gems
D) It runs the Rails application in development mode

Answer: B) It creates a new Rails application

Conclusion

In this article, we have discussed Ruby on Rails Interview Questions. Ruby on Rails continues to be a widely-used framework for building robust and scalable web applications. In this blog, we have covered various interview questions ranging from fundamental concepts to more advanced Rails functionalities. Whether you're preparing for a technical interview or looking to deepen your understanding of Rails, these questions will help you solidify your knowledge of the framework's key features, such as MVC architecture, ActiveRecord, and routing.