Ruby on Rails Interview Questions

Last updated on Nov 21, 2023

In this article, you can go through the set of Ruby on Rails interview questions most frequently asked in the interview panel. And these questions will help you crack the interview as the topmost industry experts curate these at HKR training.

Most Frequently Asked Ruby On Rails Interview Questions and Answers

What is Ruby On Rails, and how do you define it?

Ans: Ruby On Rails is defined as a server-side framework for the web applications which is used by most of the organizations. Ruby On Rails is a combination of python, making it easy for the users and compatible. It also came up with various abilities like smart talk as well as Perl, which are combined in this framework, making it one of the most trusted approaches. Ruby On Rails is a high-level programming language which has a vast scope in the current times and utilizes the object-oriented system which is considered by most of the large scale business projects.

What do you understand by the term ERB in Ruby On Rails?

Ans: The program in the web application Framework is called ERB. RRB refers to embedded Ruby. The ERB is considered when it comes to putting the codes that are associated with the Ruby in the HTML files directly. Though it is complex, a user has to do nothing and not worry about it. This is one of the best things about this ERB program.

Is it possible in the RubyRuby to develop database-driven applications in the RubyRuby Tell anyone basic approach through which the same can be developed in the RubyRuby?

Ans: Yes, it is possible to develop the database-driven applications in Ruby. One of the approaches is with the help of the model view controller pattern in Ruby. It also allows the users to ensure that the code is not very bulky when it comes to developing the same.

Give a brief idea about action controllers in Ruby On Rails?

Ans: Ruby On Rails one of the essential features in Ruby, which helps to make sure that the traffic is directed on the one hand. It also ensures that the querying of the models can be done reliably. The action controller has in organizing and specifying the data into a form which is suitable and flexible over all the different domains.

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Explain the differences between controller, helpers, views and models in Ruby?

Ans: The following are the differences between controller, helpers, views and models: 

1. Controller: Controller is referred to the subdirectory where the controller classes are located. 

2. Views: Views generally hold the display templates which are required to be filled with the data from the application. 

3. Helpers: Helpers in Ruby hold the helper class that are useful and helpful in managing the other classes. 

4. Models: Models who won the classes that generally modern the data which is stored in the application database.

Give a brief explanation about the role of active record in Ruby?

Ans: Active record in Ruby is used to make sure that the relationship among the object and database is maintained. It also helps in ensuring that all the validations are considered on time.

Give a brief idea about a pre- software requirement which was used for developing the project with Ruby On Rails?

Ans: There is a need for a web server and a database system that has to be installed in the system. The web server is used to store and control all the activities and the concerned programs related to the business. The installation of Ruby and their rails framework should be performed reliably. The users also should go and utilize the WeBrick server, which comes up with this framework. There are many different options as well that allow users to open and work with apache and TPD.

Name a few directories in Ruby and explain the purpose of each directory?

Ans: App: App is a directory that is responsible for organizing the components of your application. It is efficiently loaded with all the subdirectories that are useful. 

2. App view: They are also holding the exact display template and filling them with the data that belong to a different framework. 

Give a brief idea about garbage collection in Ruby On Rails?

Ans: Garbage collection in Ruby On Rails is used for ensuring that the point values should be removed. These values are those that are left behind after the execution of a program takes place. It also allows the users to track the objects again and again in the long run, which keeps the user relaxed and flexible. It also allows the objects that are not required to be moved to a different folder or transfer directly from memory with this approach.

. Give a brief description of rail migration?

Ans: Migration is one of the approaches which is helping the users to make the changes to the already existing database Schema in Ruby. It also helps in implementing a version control system. The most important part of the rail migration is to synchronize the objects to get some quality outcomes.

. Briefly give an idea about the object relationship model in Ruby On Rails?

Ans: The object relationship model in Ruby On Rails indicates clearly that the classes are mapped systems in the shortest possible time. The best part is that the users are free to keep up the pace in the long run. The object Relationship model also represents that the classes are mapped to the rows and tables accordingly.

. Give a brief idea about the class libraries in Ruby?

Ans: The class libraries in Ruby usually refer to the variety of domains such as thread programming, various domains, data types, etc. 

. Give a brief idea about the positive aspects of Rails?

Ans: Wales has come up with the following features like: 

1. Active record: The active record helps in saving the object to the database through the active record framework. The rails version of Active record Framework helps in identifying the column in a schema and is responsible for binding them automatically to your domain objects using the metaprogramming. 

2. Metaprogramming: Rails utilizes code generation, but for heavy lifting purposes, it will rely on metaprogramming. Hence Ruby is considered as one of the best methods of programming language. 

3. Scaffolding: Rails having the ability to create the temporary code automatically or scaffolding. 

4. Built-in testing: Race provides support code call harmless and features that make the steps to write and execute accordingly. 

5. Convention over configuration: Range does not require any much configuration if you follow the naming convention carefully. 

6. Three Environments: Rails provides its extensive support for the three default environments, like testing development and production.

. Elucidate the differences between string and symbol?

Ans: String and symbol act in the same way but they differ in their behaviour which are quite the opposite to each other. Difference light and the object_id, process tune and memory when they are used together. The symbol belongs to which category of immutable objects Where are strings belongs to the category of mutable objects.

.What are the different operations that rail migration can do?

Ans: The following are the different operations that the rails migration can do. 

1. Create a table 

2. Rename table 

3. Drop table 

4. Add a column 

5. Change column 

6. Rename column 

7. Remove column 

. What do you understand by mixin in rails?

Ans: Mixing in Ruby e provides an alternative to the multiple inheritances, by making use of the mixin models which can be imported inside another class.

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.How do you differentiate or define instance variable, global variable and class variable in Ruby? Explain how you can run Rails applications without creating databases?

Ans: The Ruby instance variable begins with -@ 

The Ruby class variables begin with --@@ 

The Ruby Global variables begin with -$. 

You can execute your application by uncommenting the line in environment.rb

path=> rootpath conf/environment.rb

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

. Give a brief idea about the limits of Ruby on Rails?

Ans: Ruby on Rails is designed for creating a web application using MVC. This might make rails not useful for the programmers. Some of the features that rail does not provide its support for a replacement below: 

1. Linking to multiple databases at once 

2. Soap Web Services 

3. Foreign key in the database 

4. connection to various database servers at once

. What is MVC principle stands for in Ruby, and what are the sub-systems in which it divides the work of an application?

Ans: MVC stands for the model view controller. There are different subsystems that will help in dividing the work of an application. They are represented below. 

1. Action controller 

2. Action view 

3. Active record

. Give a brief idea about the looping structures available in Ruby? Name the two types of scaffolding in Ruby?

Ans: The following are the looping structures available in Ruby. 

1. For loop, while loop, until loop. 

2. The Other structure would be to explain the situations in which you would use one over the other. 

There are different types of scaffolding in Ruby. They are static scaffolding and dynamic scaffolding.

. Give a brief explanation about rail observers?

Ans: Rail Observers is one of the components that is similar to the callback. The reign of service can be deployed directly in case the methods are not integrated with the life cycle of the object. Rail Observers allows users to attach the observer to any file and perform the reverse action by the user.

. Can you list out the instructions for installation of Ruby on Windows OS?

Ans: 1. You will need to make sure and check that the version of the Ruby is compatible with the OS, and it should be designed to be installed on the windows. 

2. You need to pay attention to the installation of the Ruby properties. 

3. You might need to download and install an installation package from Ruby's official website. 

4. The same has to be installed in the system default memory 

5. You will also need to install the rails through RubyGems. 

6. Check the version of the rail.

. What are the databases with which the Rails can easily work without facing any compatibility problem?

Ans: The databases that are flexible to work without any compatibility problem are dB2, MySQL, SQL, SQLite, PostgreSQL.

. What do you understand by the term scaffolding, and what are the advantages that Ruby can offer when it comes to the same?

Ans: Scaffolding refers to the process which has to be implemented during the early stage of development. Whenever we develop the projects, the user's need to write the codes in the first stage of development, these codes that are written will help in building the applications in a very reliable manner. And there is a need to keep close eye contact on the working of some of the major components in the application using this approach. In Ruby, scaffolding is done automatically, and the users are allowed to concentrate on the code development from the first day of the development phase.

. What are the basic conditions to be followed while preparing a nearby document in Ruby?

Ans: It is important to keep the code between <%and>%. This will help in incorporating solutions in the Ruby environment. It is the same thing that needs to be printed, then the same needs to be placed in <%+=and%>.

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. Explain how you can declare a block in Ruby?

Ans: A Block can be declared in Ruby then enclosing it within braces ({}). You can also invoke a block using the yield statement.

. Explain about Dig, Float and Max?

  • Float class is used whenever the function changes constantly.
  • Dig is used whenever you want to represent a float in decimal digits.
  • Max is used whenever there is a huge need for Float.

. Explain what is the purpose of RJs in Rails?

Ans: RJs is referred to as a template that helps in producing JavaScript which runs in an eval block by the browser in response to an AJAX request. It is sometimes used for defining the JavaScript, Prototype and helpers provided by Rails.

.Explain what a sweeper is in Rails?

Ans: Sweepers are responsible for expiring or terminating caches when model objects change.

.Explain what is rake in Rails?

Ans: Rake is a Ruby Make; it is a Ruby utility that substitutes the Unix utility 'make', and uses a 'Rakefile' and '.rake files' to build up a list of tasks. In Rails, Rake is used for normal administration tasks like migrating the database through scripts, loading a schema into the database, etc.

. What are Rails Filters, and how many are there?

Ans. Filters are the methods that execute "before", "after", or "around" a controller's action. These filters are helpful when we make sure that a specific block of code executes with any of the action methods. There are three types of Rails Filters: Before, After, and Around.

. What is Testing in Ruby on Rails?

Ans. Ruby on Rails also uses an individual database Ruby Test::A for testing purposes which is a unit testing library. It uses the Rake utility to execute tests for Rails applications.

. Name the Ruby on Rails default environments.

Ans. It has the following default environments:- Development, Testing, and Production.

. What are the types of Access Modifiers available in Ruby?

Ans. Three access modifiers are available in Ruby - Public, Protected, and Private.

. Define what RVM is in Ruby?

Ans. RVM, or Ruby Version Manager, is a command line tool that enables us to manage and work efficiently in various Ruby environments. Also, we can use RVM to install and manage multiple Ruby versions and switch between them easily.

. What is meant by Rails Console?

Ans. Rails Console in Ruby on Rails is a command line program that helps to interact with the Rails applications. It uses the Rails Environment's full potential and the Ruby on Rails language. Also, it is an extension of the robust IRB shell that holds the complete Rails development environment features.

. Define WEBrick Web Server?

Ans. A Webrick web server is wholly written in Ruby language and is a Ruby library that provides HTTP web servers. We can configure it as an HTTPS, a Proxy, or a virtual server. Moreover, it supports different platforms like Windows, Unix, macOS, etc.

. Is Rails a Web Server?

Ans. Rails or Ruby on Rails is an MVC and a server-side web application framework that offers a default structure for web services, a web page, and a database.

. What are the types of Scaffolding available in Ruby on Rails?

Ans. Scaffolding has two types- Static and Dynamic.

. What are Fixtures in Rails?

Ans. In Rails, fixtures arrange data that we want to insert in our unit testing. When Rails produces the relevant tests for our controllers and models, they are automatically built. Moreover, we cannot access them while running the programme, but they are used for testing.

. Define the super function used in Rails?

Ans. In Ruby on Rails, a super function or a keyword to call or invoke the superclass implementation of the existing method. Also, it helps to pass all arguments automatically to the parent method from the child method.

. Define the variable's naming convention in Rails?

Ans. In Rails, the variable's names are written in lowercase; if there are different names, they are separated by an underscore.

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. What are the Procs and Blocks in Ruby on Rails?

Ans. In Rails, procs are the objects and an important feature of the Ruby programming language. Blocks are the codes that take inputs from the arguments and give back the value. Procs help us pass blocks on every side and provide a way to store the code block to execute the same later.

. Define what Bundlers are in Rails?

Ans. In Rails, bundlers provide a continuous environment for the Ruby apps by tracking and installing the right gems as per requirement. They ensure that ruby should find all the required gems within the GemFile.

. What are the Caching levels available in Rails?

Ans. The three caching levels available in Ruby on Rails are- Fragment, Page, and Action.

. What is meant by Action Cable in Ruby on Rails?

Ans. Action cable is a type of framework that continuously integrates with the rest of the Rails applications through WebSockets. It also allows us to add real-time features to the rails apps much faster.


Most of the organizations are now relying on the tools and softwares that are extensively helping them in driving the business needs on time with efficiency. They are also looking for individuals who know the tools, programming languages and frameworks that would help them over and above during the developmental and incremental phases of the businesses. I hope the above information is helpful to you. The above questions will help you crack the interview. I would also suggest and recommend you to get trained and certified in the key technologies that are building a promising career for the individuals.

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Kavya works for HKR Trainings institute as a technical writer with diverse experience in many kinds of technology-related content development. She holds a graduate education in the Computer science and Engineering stream. She has cultivated strong technical skills from reading tech blogs and also doing a lot of research related to content. She manages to write great content in many fields like Programming & Frameworks, Enterprise Integration, Web Development, SAP, and Business Process Management (BPM). Connect her on LinkedIn and Twitter.

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