Root route in Ruby on Rails - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What does this root route configuration do?

Given this Rails route configuration, what will be the behavior when a user visits the root URL of the application?

Ruby on Rails

Rails.application.routes.draw do
  root 'welcome#index'
end

A It directs the root URL to the index action of the WelcomeController.

B It causes a syntax error because root must be inside a namespace block.

C It redirects the root URL to the show action of the WelcomeController.

D It sets the root URL to render a static HTML page named index.html.

💡 Hint

Think about what the 'root' method does in Rails routing.

The root 'welcome#index' line tells Rails to send requests to the root URL ('/') to the index action of the WelcomeController. This is the standard way to set the homepage of a Rails app.

📝 Syntax

intermediate

Identify the syntax error in this root route declaration

Which option correctly fixes the syntax error in this root route declaration?

Ruby on Rails

Rails.application.routes.draw do
  root to: 'home#main'
  root 'home#main'
end

A Change 'root to:' to 'root from:' to fix the syntax.

B Replace 'root' with 'get' to fix the syntax.

C Add parentheses: root(to: 'home#main') to fix the syntax.

D Remove the duplicate root line; only one root route is allowed.

💡 Hint

Rails only allows one root route per application.

Having two root declarations causes a routing conflict. You must have only one root route. Both root to: 'home#main' and root 'home#main' are valid, but only one should be present.

❓ state_output

advanced

What is the output when visiting root with this controller?

Given this controller and root route, what will the user see when visiting '/'?

Ruby on Rails

class HomeController < ApplicationController
  def main
    render plain: 'Welcome Home!'
  end
end

Rails.application.routes.draw do
  root 'home#main'
end

A The browser renders the default Rails welcome page.

B The browser shows a 404 Not Found error.

C The browser displays the text: Welcome Home!

D The browser displays an empty page with status 200.

💡 Hint

Look at the render method used in the controller action.

The main action renders plain text 'Welcome Home!'. Since the root route points to home#main, visiting '/' shows this text in the browser.

🔧 Debug

advanced

Why does this root route cause an error?

This root route causes an error when visiting the root URL. What is the cause?

Ruby on Rails

Rails.application.routes.draw do
  root 'dashboard#show'
end

A The root route must be defined inside a namespace block.

B There is no DashboardController defined with a show action.

C The root route must use double quotes, not single quotes.

D The root route cannot point to a show action.

💡 Hint

Check if the controller and action exist in the app.

If the controller or action does not exist, Rails raises an error when the route is accessed. The root route must point to a valid controller and action.

🧠 Conceptual

expert

What happens if multiple root routes are defined?

Consider this routes file with multiple root routes. What will happen when the Rails server starts?

Ruby on Rails

Rails.application.routes.draw do
  root 'pages#home'
  root 'dashboard#index'
end

A Rails raises a routing error because only one root route is allowed.

B Rails uses the last root route defined and ignores the first.

C Rails merges both root routes and randomly picks one at runtime.

D Rails starts normally and both root routes work depending on user role.

💡 Hint

Think about uniqueness of the root route in Rails routing.

Rails requires exactly one root route. Defining multiple root routes causes a routing error on server start.