Ruby on Rails Developer Interview Questions
At the intersection of simplicity and productivity lies Ruby on Rails, an ever-popular web application framework. This guide serves to help recruiters and employers hone in on the top talent in the RoR arena. With a blend of technical and situational interview questions, you can ascertain candidates' mastery over the framework, as well as their ability to craft scalable and maintainable applications.
What is Ruby on Rails?
Answer: Ruby on Rails, often just Rails, is a web application framework written in the Ruby language. It emphasizes convention over configuration and follows the RESTful application design.
2.
What is the difference between Ruby and Ruby on Rails?
Answer: Ruby is a dynamic, object-oriented programming language, while Ruby on Rails is a web application framework built using Ruby.
3.
Explain the principle of "Convention over Configuration" in Rails.
Answer: Rails uses sensible defaults to eliminate the need for extensive configurations, meaning a developer can get up and running faster, making assumptions based on convention.
4.
What is the MVC architecture in Rails?
Answer: MVC stands for Model, View, Controller. It divides application work into three interconnected components: Model deals with data, View handles the presentation, and Controller manages requests & ties Model and View.
5.
What are migrations in Rails?
Answer: Migrations are a way to alter database schema over time in a consistent and organized manner. They're a set of instructions Rails uses to modify the database.
6.
How do you install a specific version of a gem?
Answer: Use gem install [gemname] -v [version number].
7.
Explain the purpose of yield in Rails layouts.
Answer: yield is used in layouts to render the content of views. It tells Rails to put the rendered view in that particular spot of the layout.
8.
What is ActiveRecord, and how does it work?
Answer: ActiveRecord is the ORM (Object-Relational Mapping) layer in Rails. It abstracts and simplifies common database interactions, allowing developers to interact with databases using Ruby.
9.
Describe the Rails asset pipeline.
Answer: The asset pipeline compiles, minifies, and serves web assets. It's a framework to concatenate and serve JavaScript, CSS, and images.
10.
What are filters or callbacks in Rails, and when are they used?
Answer: Filters/callbacks are methods that Rails runs at specific times in the lifecycle of a controller action or ActiveRecord object. Examples include before_action and after_save.
11.
How do you manage sessions in Rails?
Answer: Rails provides a session method that maintains data between requests. The data stored is usually small and client-specific, like user IDs.
12.
What's the difference between has_many and has_one associations in Rails?
Answer: Both are associations between models. has_many indicates a one-to-many relationship, while has_one indicates a one-to-one relationship.
13.
What is a polymorphic association?
Answer: It's a type of ActiveRecord association that can connect a model to multiple other models using a single association.
14.
Describe CSRF protection in Rails.
Answer: CSRF protection prevents attackers from performing unauthorized actions on behalf of an authenticated user. Rails handles this with tokens embedded in forms.
15.
How can you implement caching in Rails?
Answer: Rails provides different caching techniques: page, action, fragment, and low-level caching.
16.
Explain the purpose of the respond_to method in Rails.
Answer: respond_to allows controllers to provide different outputs for different content requests, like HTML, XML, or JSON formats.
17.
What's the Rails way to manage and deploy JavaScript libraries?
Answer: Rails uses Webpacker in tandem with Yarn for managing and bundling JavaScript libraries.
18.
How do you handle API versioning in Rails?
Answer: API versioning can be managed through request headers, URL versioning, or query parameters.
19.
What is the difference between rake and rails commands?
Answer: Both are used for executing specific tasks. However, with Rails 5 onwards, many tasks originally performed with rake can now be done using the rails command.
20.
What is Turbolinks?
Answer: Turbolinks makes navigating a web application faster. It replaces only the body and the title in the head to give the appearance of a faster page load.
21.
What are concerns in Rails?
Answer: Concerns are a way to make large controllers or models more manageable by extracting reusable parts into mixins.
22.
How do you schedule background jobs in Rails?
Answer: Background jobs can be scheduled using gems like Sidekiq, Resque, or DelayedJob.
23.
What are strong parameters in Rails?
Answer: Strong parameters prevent unwanted user input by allowing developers to whitelist the permissible parameters.
24.
How do you optimize a Rails application's performance?
Answer: Optimization can include caching, database indexing, eager loading, using CDNs, and minimizing the use of gems.
25.
What is RSpec and why is it useful?
Answer: RSpec is a testing tool for Ruby. It's useful for writing cleaner, more specific tests using a human-readable domain-specific language.
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