Rails installation and setup - Practice Problems & Coding Challenges

Challenge - 5 Problems

📝 Syntax

intermediate

Correct command to create a new Rails app with PostgreSQL

Which command correctly creates a new Rails application named blog using PostgreSQL as the database?

A rails create blog -d postgresql

B rails new blog -db postgresql

C rails new blog --database=mysql

D rails new blog -d postgresql

💡 Hint

Use the rails new command with the correct database option.

The correct syntax to specify the database is -d postgresql with the rails new command. Option D uses an invalid command create, Option D uses the wrong database, and D has a wrong flag -db.

❓ component_behavior

intermediate

Behavior of rails server command

What happens when you run the command rails server in a Rails project directory?

A Starts a local web server running the Rails app on port 3000 by default

B Compiles the Rails app into a standalone executable

C Deletes temporary files and caches in the project

D Generates a new controller with default actions

💡 Hint

Think about what a server command usually does.

The rails server command launches a local web server (usually Puma) that runs your Rails application, accessible at http://localhost:3000 by default.

🔧 Debug

advanced

Error when running rails db:create

You run rails db:create but get the error: could not connect to server: Connection refused. What is the most likely cause?

A The <code>rails db:create</code> command is deprecated and should not be used

B The Rails app has syntax errors in <code>database.yml</code>

C The database server (e.g., PostgreSQL) is not running or not installed

D The Rails version is incompatible with the database adapter

💡 Hint

Check if your database service is active.

This error usually means the database server is not running or installed. Rails cannot connect to create the database. Syntax errors in database.yml would cause different errors, and the command is not deprecated.

🧠 Conceptual

advanced

Purpose of the Gemfile in Rails setup

What is the main purpose of the Gemfile in a Rails project?

A To list and manage Ruby gems (libraries) the project depends on

B To configure database connection settings

C To define routes for the Rails application

D To store environment variables for deployment

💡 Hint

Think about how Ruby projects manage external libraries.

The Gemfile lists all Ruby gems your Rails app needs. Bundler uses it to install and manage these gems. Database settings are in database.yml, routes in routes.rb, and environment variables are usually in separate files.

❓ state_output

expert

Result of running rails new without Ruby installed

What will happen if you try to run rails new myapp on a system where Ruby is not installed?

A The command will create a minimal app with only JavaScript files

B The command will fail with an error like 'rails: command not found' or similar

C Rails will download and install Ruby automatically before creating the app

D The app will be created but will not run until Ruby is installed

💡 Hint

Rails depends on Ruby to run commands.

Rails is a Ruby gem and requires Ruby installed to run. Without Ruby, the rails command is not recognized, causing a 'command not found' error. Rails does not install Ruby automatically.