CodeSubmit Interview Series

10 Top Ruby on Rails Interview Questions in 2023

Are you hiring Ruby on Rails developers? Your interview questions can help you identify the best candidates. And today, you get the 10 best Ruby on Rails interview questions. Want to learn more? Read on! 

Ruby on Rails interviews

Ruby on Rails is a server-side web application framework written in Ruby. Ruby on Rails, also known as Rails, is a model-view-controller framework, which provides default structures for a database, web pages, and a web service. 

As one of the most popular frameworks, Rails is an important part of many technical teams' tech stacks. But how do you hire Ruby on Rails developers? Here’s how to interview your candidates with the right interview questions. 

Beginner Ruby on Rails interview questions

First, let’s start with interview questions you might ask junior candidates. These are basic questions that require the candidate to have some understanding of what Ruby on Rails is and why it’s used, as opposed to deep technical knowledge (which junior candidates might now have yet). 

1. What is Ruby on Rails?


Ruby on Rails is an open-source server-side web application framework. It’s written in Ruby under the MIT license. Ruby, on the other hand, is an object-oriented programming language, which is inspired by Smalltalk, Eiffel, PERL, Ada, Basic, and Lisp. 

Rails was first created in 2004 as part of the Basecamp project management tool. It had a big impact on web app development thanks to new features like seamless database table creations, migrations, and scaffolding of views that facilitate rapid app development. Today, Ruby is used across many applications, such as GitHub, Square, Shopify, and Airbnb. Many web frameworks borrow its ideas, including Node.js, Django in Python, and Sails.js

Rails provides default structures for a database, a web service, and web pages. It makes it easier to use web standards such as XML and JSON for data transfer and HTML, JavaScript, and CSS for user interfacing. 

2. How is Ruby on Rails different from other web application frameworks? 


Note that this question isn’t about quizzing people on what paradigms Rails is built on. Instead, listen to their answer to get an idea of how well they understand the framework and why someone would choose to use Rails rather than other frameworks. 

Ruby on Rails was created with different paradigms in mind, which are programmer happiness, convention over configuration, progress over stability, the menu is omakase, no one paradigm, exalt beautiful code, provide sharp knives, value integrated systems, and push up a big tent. Most of these paradigms have a different approach than other frameworks; for instance, programmer happiness is seldom taken into account and web development has traditionally been seen as just “a tool.” 

3. Is Ruby as a language statically or dynamically typed? 


Ruby is dynamically typed, which means that you can change the type of a variable as you go. These lines of code, run one after the other, do not throw an error. 

x = 1

x = "foo"

4. What are Rails design patterns? Which ones have you used? 


Rails includes a number of design patterns, including service objects, value objects, view objects, form objects, query objects, decorators, and policy objects. The framework implements the Model-View-Controller (MVC) design pattern to reduce clutter and organize code better. With these design patterns, developers achieve the goal of “Fat Model, Skinny Controller.”

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


Class and Module: These use MixedCase and they have no underscore. Every word starts with an uppercase letter. 

Variables: All letters are lowercase and words are separated by underscores. 

Model: Models are represented by unbroken MixedCase. They always have singular with the table name. 

Controller: Represented in plural form, so that OrdersController would be the controller for the order table.

Database Table: The database table name has lowercase letters and underscores between words. All table names should be in plural form. 

6. What’s the meaning of “Fat models, skinny controllers”? 


Controllers just pass information between views and models, so business logic shouldn’t exist in controllers, but in models. Logic becomes easier to unit test and reuse. However, “Fat models, skinny controllers” isn’t necessarily recommended in large apps. 

Advanced Ruby on Rails interview questions

What are some advanced Ruby on Rails interview questions? These questions are designed for more senior Ruby on Rails developers. Read on to learn more!

7. How does Ruby on Rails implement Ajax (Asynchronous Javascript and XML)? 


Ajax, which uses asynchronous data transfer between the browser and web server, retrieves web pages from the server. Ruby on Rails triggers Ajax in these ways: 

  • Web client calls the server: XMLHttpRequest, a JavaScript method, sends data linked with the trigger to an action handler on the server. The data might be the whole form, the text in the entry field, or the ID of a checkbox. 

  • Some trigger fires: The triggers include a user making changes to the data in the field or on a form or clicking a link or a button. 

  • Client receives the response: Rails generates client-side JavaScript automatically. It receives the HTML fragment and uses it to update a specific part of the current. 

8. What is the role of Rails Controller? 


The Rails controller, which is the logical center of an app, facilitates the interaction between users, the model, and views. 

  • It can route external requests to internal actions and handles URLs extremely well.

  • It also regulates helper modules so that the capabilities of the view templates can be extended without bulking their code. 

  • And it regulates sessions so that users are given the impression of an ongoing interaction with the applications. 

9. What is Rack? 


Rack is an API between Rails and the web server. With it, you can plug in and swap frameworks like Rails with Sinatra or Unicorn with Puma.

10. What is the function of garbage collection in Ruby on Rails? 


Garbage collection includes the following functions:

  • Enables the removal of the pointer values, which are left behind when the execution of a program ends. 

  • Frees the developer from tracking the object that is being created dynamically on runtime. 

  • Gives the advantage of removing the inaccessible objects from the memory and allows other processes to use the memory. 

Over to you!

That’s it! Now you know what Ruby on Rails interview questions to prepare for your next interview. 

But interviews are only part of the equation. You also need a skill assessment tool. 

CodeSubmit helps you identify the best candidates based on their real-world skills. 

Sign up for a free CodeSubmit trial! (No credit card required.)