Route definition in routes.rb in Ruby on Rails - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of this route helper?

Given the following route definition in routes.rb, what URL will posts_path generate?

Rails.application.routes.draw do
  resources :posts, only: [:index, :show]
end

A "/posts"

B "/posts/index"

C "/posts/show"

D "/post"

💡 Hint

The posts_path helper corresponds to the index action URL for posts.

The resources :posts creates RESTful routes. The posts_path helper generates the URL for the index action, which is /posts.

📝 Syntax

intermediate

Which route definition correctly creates a nested resource?

You want to define routes so that comments belong to posts, accessible via URLs like /posts/:post_id/comments. Which option correctly defines this in routes.rb?

A

resource :posts do
  resource :comments
end

B

resources :posts do
  resources :comments
end

C

resources :comments do
  resources :posts
end

D resources :posts, :comments

💡 Hint

Nested resources are defined by placing one resources block inside another.

Option B correctly nests comments inside posts, creating URLs like /posts/:post_id/comments.

🔧 Debug

advanced

Why does this route cause a routing error?

Given this route definition:

get 'profile/:id', to: 'users#show'

And this URL request: /profile
What error will Rails raise?

A ArgumentError

B ActionController::UrlGenerationError

C NoMethodError

D ActionController::RoutingError

💡 Hint

The URL is missing a required parameter defined in the route.

The route expects an :id parameter, but the URL /profile does not provide it. This causes a routing error because no matching route is found.

❓ state_output

advanced

What is the HTTP verb and path for this custom route?

Consider this route in routes.rb:

post 'subscribe', to: 'newsletters#subscribe'

What HTTP verb and path does this route respond to?

A POST /subscribe

B DELETE /subscribe

C PUT /subscribe

D GET /subscribe

💡 Hint

The first word in the route definition is the HTTP verb.

The route responds to HTTP POST requests at the path /subscribe.

🧠 Conceptual

expert

How many routes are created by this line?

What is the total number of routes generated by this line in routes.rb?

resources :articles, only: [:index, :show, :create, :update, :destroy]

A 3

B 7

C 5

D 6

💡 Hint

Each action in the only list creates one route.

The only option limits routes to the specified actions. Each action corresponds to one route, so 5 actions create 5 routes.

Practice

1. What is the purpose of defining routes in the routes.rb file in a Rails application?

easy

A. To manage user sessions

B. To write database queries

C. To style the web pages

D. To connect URLs to specific controller actions

Solution

1. Step 1: Understand the role of routes in Rails

   Routes define how incoming web requests are matched to controller actions.

2. Step 2: Identify the correct purpose

   Connecting URLs to controller actions allows the app to respond correctly to user requests.

3. Final Answer:

   To connect URLs to specific controller actions -> Option D

4. Quick Check:

   Routes link URLs to actions [OK]

Hint: Routes map URLs to controller actions [OK]

Common Mistakes:

• Confusing routes with database queries
• Thinking routes handle styling
• Assuming routes manage sessions

2. Which of the following is the correct syntax to define a GET route for the URL /home that maps to the index action of the pages controller?

easy

A. route get '/home' => 'pages#index'

B. get 'pages#index', to: '/home'

C. get '/home', to: 'pages#index'

D. post '/home', to: 'pages#index'

Solution

1. Step 1: Recall the syntax for GET routes in Rails

   The correct syntax is get 'url', to: 'controller#action'.

2. Step 2: Match the URL and controller#action correctly

   get '/home', to: 'pages#index' correctly uses get '/home', to: 'pages#index'.

3. Final Answer:

   get '/home', to: 'pages#index' -> Option C

4. Quick Check:

   GET route syntax = get 'url', to: 'controller#action' [OK]

Hint: Use get 'url', to: 'controller#action' for GET routes [OK]

Common Mistakes:

• Swapping URL and controller#action positions
• Using post instead of get for GET routes
• Incorrect syntax like 'route get'

3. Given the following route definition in routes.rb:

resources :articles, only: [:index, :show]

What URLs will be available and which controller actions will they map to?

medium

A. /articles (GET) -> articles#index and /articles/:id (GET) -> articles#show

B. /articles/new (GET) -> articles#new and /articles/:id/edit (GET) -> articles#edit

C. /articles (POST) -> articles#create and /articles/:id (PATCH) -> articles#update

D. /articles/:id (DELETE) -> articles#destroy and /articles (GET) -> articles#index

Solution

1. Step 1: Understand the resources with only option

   It limits routes to only index and show actions.

2. Step 2: Identify URLs and actions for index and show

   index maps to GET /articles, show maps to GET /articles/:id.

3. Final Answer:

   /articles (GET) -> articles#index and /articles/:id (GET) -> articles#show -> Option A

4. Quick Check:

   resources with only index, show = GET /articles and GET /articles/:id [OK]

Hint: Only index and show create GET /collection and GET /collection/:id [OK]

Common Mistakes:

• Assuming all RESTful routes are created
• Confusing HTTP verbs for actions
• Mixing up new/edit with index/show

4. Identify the error in this route definition:

get '/profile', controller: 'users', action: 'show'

medium

A. URL should not start with a slash

B. Missing 'to:' keyword before controller#action

C. Should use 'post' instead of 'get'

D. Controller name should be capitalized

Solution

1. Step 1: Check correct syntax for get route with controller and action

   The correct syntax uses to: 'controller#action', not separate keys.

2. Step 2: Identify the missing 'to:' keyword

   The given code misses to: and incorrectly uses separate keys.

3. Final Answer:

   Missing 'to:' keyword before controller#action -> Option B

4. Quick Check:

   Use get '/url', to: 'controller#action' [OK]

Hint: Use 'to:' keyword for controller#action in routes [OK]

Common Mistakes:

• Omitting 'to:' keyword
• Using wrong HTTP verb
• Incorrect URL format

5. You want to create routes for a blog with posts and nested comments. Which route definition correctly creates RESTful routes for posts and nested comments inside routes.rb?

hard

A. resources :posts do
resources :comments
end

B. resources :posts, comments: true

C. resource :posts do
resource :comments
end

D. get '/posts/:post_id/comments', to: 'comments#index' only

Solution

1. Step 1: Understand nested resources syntax

   Nested resources are defined by placing one resources block inside another.

2. Step 2: Identify correct nested syntax for posts and comments

   resources :posts do resources :comments end correctly nests comments inside posts using a block.

3. Final Answer:

   resources :posts do resources :comments end -> Option A

4. Quick Check:

   Nested resources use block syntax [OK]

Hint: Nest resources inside block for nested routes [OK]

Common Mistakes:

• Using singular 'resource' instead of plural 'resources'
• Trying to pass nested resources as options
• Defining only one route manually