Hiring for Project Development: 9 Types of Ruby on Rails Interview Questions to Ask a Developer

When you’re scouting for a RoR partner to bring your project to life, you’re like a Sherlock with a checklist. You dive into numerous factors, such as the company’s location, hourly rates, testimonials on platforms like Clutch.co or Goodfirms, and its published case studies.

As a potential client, you have the right to get information from the company you are planning to trust with your project idea. It’s ok to be curious about its processes, asking for its specialists’ experience, and even how the company picks them for projects.

Since 2013, Rubyroid Labs’ team has successfully produced over 200 mobile and web applications. Our devs’ can-do attitude, willingness to listen to the clients’ needs, and cracking tough problems have won us the highest 5-star rating on Clutch.co, putting us in the top 3 Ruby on Rails development companies.
If you need a high-quality team with transparent working processes and smooth communication to join your project, contact us.

When it comes to hiring Ruby on Rails developers, we’re sure that having superb technical skills is not enough. Strong communication skills, as well as the ability to manage time and workload efficiently, are just as important as Ruby coding expertise.

This post will help you understand how to identify talented developers for Ruby on Rails projects. Furthermore, you will gain vital insights for conducting technical interviews when hiring programmers for your own project.

Contents

1. A Great Ruby on Rails Developer. Who is it?
2. Ruby On Rails Interview Questions And Answers Checklist by Rubyroid Labs
3. Most Commonly Asked Ruby Code Questions
4. Ruby on Rails Interview Questions for Experienced and Junior Programmers
5. Developer’s Security Knowledge: What to Ask?
6. Top Questions about Code Refactoring
7. How to Test a Developer’s Soft Skills
8. 5 Lifehacks for a Successful Ruby on Rails Developer Interview
9. Wrapping Up

A Great Ruby on Rails Developer. Who is it?

In an era of high-demand for skilled talent, which has been prevalent in the tech market since 2023, finding an exceptional Rails developer can often feel like searching for a unicorn.

The reason is a mismatch between rapidly evolving technologies, the high demands of employers for skilled specialists, and the reality that the actual skill level of programmers often falls short. All this has significantly increased the hunger for real professionals, as the success of any project depends on the knowledge and expertise of the developer.

Let’s explore the key traits to look for in a full-stack Ruby developer to ensure the delivery of high-quality applications or software.

• Deep Ruby on Rails Knowledge

A Ruby on Rails programmer stands out for their profound understanding of the framework and its conventions. With proficiency in using built-in features like ActiveRecord for database management and ActionView for crafting user interfaces, they can easily navigate the Rails ecosystem, leveraging popular gems and libraries to produce clean code.

• Object-Oriented Programming (OOP) Principles Understanding

Ruby on Rails is built on the core concepts of Object-Oriented Programming (OOP). A cool programmer knows the key OOP principles such as encapsulation, inheritance, and polymorphism. This helps them skillfully design and develop classes, objects, and modules, leading to the creation of code that is reusable, straightforward, and user-friendly.

• Expertise in MVC Architecture

Understanding MVC (Model-View-Controller), which is a basic architectural pattern in Ruby on Rails, ensures that the engineer can create logical models, efficient controllers, and intuitive views, thereby guaranteeing scalability and maintainability.

• Proficiency in Database Management

Being experienced in database work and familiar with ActiveRecord, Rails’ ORM (Object-Relational Mapping) tool, a Ruby on Rails programmer can build database schemas, craft optimized queries, and manage migrations. Their focus on database performance is evident in their ability to work with various database platforms, including PostgreSQL and MySQL.

• Testing and Test-Driven Development (TDD) Knowledge

A skilled developer is strong at using testing frameworks like RSpec or MiniTest and adheres to test-driven development practices. They create comprehensive test suites, ensuring the application’s stability and reliability and minimizing bugs and regressions.

• Front-End Technology Familiarity

Apart from Ruby on Rails back-end expertise, an outstanding Ruby programmer also has skills in front-end technologies like HTML, CSS, and JavaScript and can collaborate with front-end engineers, implement responsive designs, and develop interactive user interfaces with frameworks such as React or Vue.js.

• Effective Problem-Solving Abilities

Another key feature of a reliable Ruby on Rails programmer is a methodical and logical mindset, which enables them to break down complex problems into manageable parts. These problem-solving skills contribute to efficient development, allowing them to navigate obstacles and deliver high-quality solutions.

• Strong Communication and Teamwork

The abilities of conducting dialogue and working in a team are key to successful development projects. A competent Ruby on Rails developer communicates clearly with team members, stakeholders, and clients. They listen actively, clarify requirements, share ideas, and function well in a team. All this fosters a smooth and productive development process.

Ruby On Rails Interview Questions And Answers Checklist by Rubyroid Labs

At Rubyroid Labs, we deal with projects across various industries and provide multiple Ruby on Rails development services to clients from Tokyo to Los Angeles and from Berlin to Melbourne.

Maintaining a pure reputation is one of our top values. That’s why we hire programmers who are excellent at writing code and can easily integrate into our existing team.

Every interview with a tech engineer in our company consists of carefully selected questions on our special checklist, which help uncover the true traits and knowledge level of a potential employee. The way a programmer answers the questions shows the proficiency and personality of a candidate.

We are sharing a list of some of our frequently asked questions and answers with you. They will undoubtedly help you interview programmers for your project.

Let’s skip to them.

What is Ruby on Rails?

Ruby on Rails is a web application framework that uses the Ruby programming language. It follows the Model-View-Controller (MVC) architectural pattern and provides developers with a set of conventions, tools, and libraries to build robust and scalable web applications.

What are Ruby on Rails naming conventions?

In Rails, there are specific naming conventions to maintain consistency and make the code more readable.

• Variables: All letters are lowercase, and words are separated by underscores.
• Class and Module: Modules and classes use CamelCase, starting with an uppercase letter for each word.
• Database Table: Database table names should be in lowercase with underscores between words, and they should be in plural form (e.g., invoice_items).
• Model: Represented with unbroken CamelCase and always in singular form, corresponding to the table name.
• Controller: Controller class names should be in plural form, representing the associated table (e.g., OrdersController for the order table).

What is “yield” in Ruby on Rails?

In Ruby on Rails, “yield” is a keyword used within a method to invoke a code block that is passed to the method. It allows you to execute a block of code at a specific point within the method’s implementation.

What is The ORM Model in Rails?

ORM, or Object Relationship Model in Rails, is the technique where the classes are mapped to the table in the database and objects are directly linked to the table’s rows. It enables programmers to interact with the database using object-based paradigms, treating tables as classes and rows as objects. Rails’ built-in ORM, called Active Record, simplifies database operations and eliminates the need for writing raw SQL commands.

Mention What is the Difference Between False and Nil in Ruby?

In Ruby, “false” is an object of the FalseClass, representing a boolean value of false. On the other hand, “nil” is an object of the NilClass, indicating the absence of a value or the lack of an assigned object. False and nil have different object_ids, with false having an object_id of 0 and nil having an object_id of 4.

What is the Rails Active Record in Ruby on Rails?

Rails Active Record is the Object/Relational Mapping (ORM) layer included in Rails. It provides an interface to interact with the relational database, connecting tables to classes, rows to objects, and columns to object attributes. Active Record simplifies database operations, such as querying, inserting, updating, and deleting records, by providing a high-level abstraction.

What is Rake in Rails?

Rake is a build utility in Rails that serves as a replacement for the traditional “make” utility in Unix-like systems. It uses a Rakefile, which contains a set of tasks defined using Ruby’s DSL (Domain-Specific Language). Rake tasks are used for various administrative tasks in Rails, such as running database migrations, loading a schema, and executing custom scripts.

What is the Difference Between Observers and Callbacks in Ruby on Rails?

In Ruby on Rails, Observers and Callbacks are both used to execute code at specific points during an object’s life cycle.

• Observers: Observers are used when the method is relatively associated with the object’s life cycle. They can be attached or detached at any time and have a longer lifespan. Observers are commonly used for tasks like displaying values from a model in the UI or updating a model based on user input.
• Callbacks: they are short-lived methods that are directly associated with an object’s life cycle. They are called at specific moments, such as validation, creation, updating, or deletion of an object. A Rails callback provides a way to hook into these events and execute custom logic.

What is Rails Migration?

Rails Migration is a feature that allows programmers to modify the database schema of a Rails application using a domain-specific language (DSL) instead of writing SQL scripts. Migrations provide a version control-like system for managing database changes, enabling tech engineers to create, change, and revert database structures in a consistent and organized manner. Migrations can be rolled back and are tracked alongside the application source code.

What is the Difference Between ActiveSupport’s “HashWithIndifferentAccess” and Ruby’s “Hash”?

The “HashWithIndifferentAccess” class in ActiveSupport treats symbol and string keys as equivalent and gives access values using either symbols or strings. On the other hand, Ruby’s “Hash” class uses a stricter comparison for keys, considering them different if they have different types. This means that a comparable string key will not retrieve the value associated with a symbol key in a Ruby hash.

Explain What Cross-Site Request Forgery (CSRF) is and How Rails is Protected Against It.

Cross-Site Request Forgery (CSRF) is a type of attack where an attacker tricks a user’s browser into making an unintended request on a different website, causing potential harm or unauthorized actions. The attack leverages the trust between the user’s browser and the target website.
To prevent CSRF attacks, it is necessary to add “protect_from_forgery” to ApplicationController. In this case, Rails will require a CSRF token to perform the request. A CSRF token is provided as a hidden field in all forms produced using Rails form builders.

Explain What are Strong Parameters?

Many Rails projects use Strong Parameters, also known as Strong Params, to improve the security of data submitted via forms. Strong params enable programmers to specify which parameters are accepted and utilized in the controller. Any unnecessary or possibly harmful parameters will be ignored and effectively filtered away, leaving just the anticipated parameters. This is especially important when utilizing Active Model bulk assignments, as several parameters can be given at the same time.

Most Commonly Asked Ruby Code Questions

One common challenge we’ve noticed while searching for Ruby on Rails programmers is that some of them lack a solid understanding of the very basics—the Ruby programming language.

As our goal is to hire forward-thinking software engineers who not only create code but also have knowledge of Ruby’s fundamentals, we always begin interviews by evaluating their basic understanding of Ruby.

Object-Oriented Programming Questions (OOP)

The comprehension of basic principles such as OOP indicates a tech engineer’s educational background. It is as crucial as having a strong foundation for building a sturdy house.

Below, you will find a list of OOP questions.

Business Applications

Simply knowing the basics is not enough for a Ruby on Rails programmer position. At an interview, they must also demonstrate their ability to write code for business applications.

Rack is a popular interface for Ruby application development, so we pose specific questions related to it. Rack functions as a middleware layer, allowing programmers to easily create applications by providing a single interface between web servers and Ruby frameworks.

A short list of the questions below helps to identify a tech engineer’s level of knowledge about Rack.

Ruby Gems

Discussing Ruby gems is a perfect chance for a candidate to prove mastery of the fundamental structure of a gem library. A programmer will utilize different gems in app development projects, starting from code writing to bug fixing in the existing apps built by other engineers.
So, we examine the candidate’s ability to comprehend Ruby gems and describe them through the questions below.

Ruby on Rails Interview Questions for Experienced and Junior Programmers

The Ruby on Rails part of an interview tests the programmer’s proficiency in the Rails framework and can be applicable to engineers of all experience levels. A skilled specialist should answer three types of questions:

• General questions about Ruby on Rails framework
• Questions about routing, controllers, and views as key parts of business applications
• ActiveRecord-related questions

Ruby on Rails Basics

The list of top Ruby on Rails interview questions below indicates not only the expertise of a tech engineer but also how well they understand all the processes and peculiarities.

Routing, Controllers and Views

A programmer’s know-how in routing, controllers, and views shows their ability to create robust and user-friendly business applications. These are the essential components of Ruby on Rails web development.

Routing knowledge indicates how incoming web requests are sent to the correct controller actions. This guarantees that a tech engineer can create clean, efficient URL structures.

With the help of expertise in Rails controllers, the programmer can manage critical features such as business logic, data manipulation, and client requests.

Views knowledge shows the engineer’s competence in developing intuitive user interfaces, generating dynamic content, and using templating languages.

To test a candidate’s knowledge of routing, controllers, and views and their logic, we use the questions below.

Active Record

Checking the expertise in Active Record helps us examine the candidate’s skills in designing models, creating associations between distinct entities, running database queries, and handling data validations.

Below are the questions for Active Record.

Developer’s Security Knowledge: What to Ask?

Every Ruby on Rails application must be protected against all types of cyber attacks. Our developers are experts in security issues and have strong skills in safeguarding the code from invasions.
Therefore, when selecting a new programmer to join our team, it is crucial for us to assess their knowledge of security. The candidate should be familiar with the existing best practices for protection and understand when to apply them.

The questions provided in the list below effectively reveal the programmer’s experience not only in Ruby on Rails security but also in fundamental web security concepts.

Top Questions about Code Refactoring

High-quality code and seamless application performance are two crucial points of app development that can be achieved through a programmer’s code refactoring skills.
Refactoring means brushing up the written code to make it cleaner and more maintainable.

We expect our Rails developers to deliver code of top quality to our clients, so they should understand how to keep a proper code structure and enhance the app’s performance without changing the behavior of the code.
When a programmer is skilled in refactoring, the team will be able to improve the app in the future according to changing demands.

To test the candidate’s refactoring skills, we employ the following questions. Note that you can use all of them during your project tech interviews.

How to Test a Developer’s Soft Skills

When working on long-term projects with a development team, it is important for a programmer to possess not only technical knowledge and skills but also certain personal qualities. Building projects can take months or even years, and the development team spends a significant amount of time together, much like a family. Hence, effective communication and positive personal traits are crucial for creating a pleasant and friendly working environment within the project.
To better understand the applicant’s personality and their thoughts about their future, there are some questions below.

5 Lifehacks for a Successful Ruby on Rails Developer Interview

One of the most challenging aspects of the interviewing process is dealing with the nervousness of the interviewees. This stress often hinders their ability to discover their skills effectively. To ensure we don’t miss out on a good employee, it is crucial to create a comfortable atmosphere during the interview. Here are five tips to make the interview process friendly and smoother:

1. Preparation: Before the interview, review the job description and the candidate’s CV to understand his work history and the job requirements. Based on this information, highlight specific interview questions.
2. Establish a comfortable environment. Start the interview by putting the candidate at ease. Introduce yourself and explain your role in the organization. Inform the candidate about the interview process, allowing the candidate to mentally prepare.
3. Reduce candidate stress. Start the conversation with small talk and find common interests with the interviewee. Avoid sensitive topics like religion or politics and focus on hobbies, or sport & health. Pay attention to your tone and body language, creating a friendly atmosphere.
4. Use the STAR (Situation, Task, Action, Result) interview method: This technique is effective for gathering relevant information about a candidate’s capabilities. Ask generic interview questions and encourage candidates to provide specific examples of their past experiences.
5. Use follow-up questions: Don’t limit yourself to prepared interview questions. Ask follow-up questions to gain more insight into the candidate’s personality, work experience, and thought process.

In addition to these key points, it is important to take notes during the interview to remember important details. Find a balance between active listening and note-taking. Allow the candidate to ask questions to pique their interest in the job. Finally, at the end of the interview, provide a description of what the candidate can expect next.

Wrapping Up

Interviewing candidates and selecting the right one is a challenging process that can be time-consuming. However, it is crucial to invest adequate time in the candidate selection process and prioritize hiring specialists with years of experience rather than settling for low-quality candidates.

At Rubyroid Labs, we understand the significance of this selection process. We have a team of over 60 talented developers, and most of them are middle- and senior-level programmers. On average, our specialists work about 2–4 years on the same project.
This means that our developers have demonstrated their commitment to continuously upgrading their skills within our company and are well-prepared to meet our clients’ interests and perform their responsibilities at the highest level of quality.

They possess the necessary expertise to handle Ruby on Rails projects efficiently. If you are in search of a dream team to develop your Ruby on Rails project, write to us and get a free quote.