Ruby on Rails Case Studies & Practical Application 2

Question 1

A Rails e-commerce app experiences N+1 queries when displaying an order list with customer names. Which fix is most appropriate?

Accepted Answer

Use Order.includes(:customer) in the controller

Answer

includes(:customer) eager-loads the association, eliminating the N+1 by fetching all customers in one query.

Question 2

You need to allow users to upload profile photos in a Rails app. Which Rails built-in handles file attachment handling?

Accepted Answer

Active Storage

Answer

Active Storage ships with Rails 5.2+ and is the officially recommended solution for file attachments.

Question 3

A multi-tenant SaaS app must scope all database queries to the current tenant to prevent data leaks. What is the safest Rails pattern?

Accepted Answer

Use a gem like acts_as_tenant that applies scoping at the model level

Answer

acts_as_tenant automatically applies tenant scopes to all queries, reducing the risk of missed manual filters.

Question 4

Your Rails API is slow because email sending is blocking web requests. What is the correct architectural fix?

Accepted Answer

Move email sending to an async job queue via Sidekiq or Active Job

Answer

Offloading email delivery to a background job keeps web requests fast and non-blocking.

Question 5

A Rails app must support both JSON API and HTML responses from the same controller action. Which Rails feature handles this cleanly?

Accepted Answer

respond_to blocks with format.html and format.json

Answer

respond_to blocks let a single action render different formats based on the client's Accept header or URL extension.

Ruby on Rails Practice Test