Config folder purpose in Ruby on Rails - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Purpose of the config folder in Rails

What is the main purpose of the config folder in a Rails application?

A It stores configuration files that set up the application environment and settings.

B It contains all the database migration files for schema changes.

C It holds the view templates for rendering HTML pages.

D It stores the user-uploaded files and assets.

💡 Hint

Think about where Rails keeps files that control app settings and environment.

The config folder contains files like database.yml, environment settings, and initializers that configure how the Rails app runs.

❓ component_behavior

intermediate

Effect of changing config/environments/production.rb

If you modify config/environments/production.rb in a Rails app, what will happen when you deploy to production?

A The changes will only apply after restarting the Rails server in development.

B The production environment will use the new settings defined in that file.

C The development environment will be affected instead of production.

D No effect, because this file is ignored by Rails.

💡 Hint

Each environment file controls settings for that specific environment.

The production.rb file holds configuration specific to the production environment, so changes here affect production behavior.

📝 Syntax

advanced

Correct syntax for database config in config/database.yml

Which option shows the correct YAML syntax for defining the default database adapter as PostgreSQL in config/database.yml?

A default: adapter: postgresql

B default = { adapter: 'postgresql' }

C

default:
  adapter: postgresql

D default: { adapter: postgresql }

💡 Hint

YAML uses indentation and colons for key-value pairs.

YAML requires a colon and indentation for nested keys. Option C correctly shows this format.

🔧 Debug

advanced

Why does Rails ignore changes in config/initializers?

You changed a file in config/initializers but your Rails app does not reflect the change after reload. Why?

A Initializers are only loaded once when the server starts, so you must restart the server.

B Initializers are cached in the browser and need cache clearing.

C Initializers only run in development, not in production.

D Initializers require a database migration to take effect.

💡 Hint

Think about when initializers run in the Rails lifecycle.

Initializers run once when the Rails server boots. Changes require a server restart to reload.

❓ state_output

expert

Output of Rails config after modifying config/application.rb

Given this snippet in config/application.rb:

module MyApp
  class Application < Rails::Application
    config.time_zone = 'Eastern Time (US & Canada)'
  end
end

What will Rails.application.config.time_zone return at runtime?

A Raises NoMethodError

B 'UTC'

C nil

D 'Eastern Time (US & Canada)'

💡 Hint

The config.time_zone setting sets the app's time zone.

Setting config.time_zone in application.rb changes the default time zone accessible via Rails.application.config.time_zone.