RESTful resource routes in Ruby on Rails - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the URL and HTTP method for the 'edit' action in a RESTful resource route?

Given a resource named articles, what is the correct URL path and HTTP method to access the edit action for the article with ID 5?

A POST /articles/5/edit

B GET /articles/5/edit

C GET /articles/edit/5

D PATCH /articles/5/edit

💡 Hint

Remember, the edit action shows a form to change an existing resource and uses GET.

The edit action in RESTful routes uses the GET method and the URL pattern /resource/:id/edit. For articles with ID 5, it is GET /articles/5/edit.

📝 Syntax

intermediate

Which route declaration creates all RESTful routes for a resource named 'products'?

In Rails routing, which line correctly generates all seven standard RESTful routes for the products resource?

A match 'products', via: :all

B resource :products

C get 'products'

D resources :products

💡 Hint

Plural form is important for multiple resources.

The resources :products declaration creates all seven RESTful routes (index, show, new, create, edit, update, destroy) for multiple products. resource (singular) is for a single resource without index.

❓ state_output

advanced

What controller action and params are triggered by this route?

Given the route resources :comments, what controller action and params hash will be called when a DELETE request is sent to /comments/42?

A Action: destroy, Params: { id: '42' }

B Action: delete, Params: { comment_id: '42' }

C Action: destroy, Params: { comment_id: '42' }

D Action: remove, Params: { id: '42' }

💡 Hint

The DELETE method on a resource with ID calls the destroy action with id param.

DELETE /comments/42 calls the destroy action in CommentsController with params[:id] = '42'. The param key is always id for RESTful routes.

🔧 Debug

advanced

Why does this custom route conflict with RESTful routes?

Consider these routes in routes.rb:

resources :users
get '/users/new', to: 'users#show'

What problem will this cause when accessing /users/new?

A The custom route overrides the RESTful 'new' action, causing the wrong controller action to run.

B The RESTful 'show' action will never be called for any user.

C It causes a syntax error in the routes file.

D No problem; both routes work fine together.

💡 Hint

Routes are matched top to bottom; custom routes can override RESTful ones.

The custom route get '/users/new' matches before the RESTful new route, so it calls users#show instead of users#new. This breaks the expected behavior for the 'new' page.

🧠 Conceptual

expert

How does Rails handle nested RESTful resource routes in URL and params?

Given these nested routes:

resources :authors do
  resources :books
end

What is the URL and params hash for accessing the 'show' action of book with ID 7 belonging to author with ID 3?

A URL: /authors/3/books/7, Params: { id: '3', book_id: '7' }

B URL: /books/7/authors/3, Params: { id: '7', author_id: '3' }

C URL: /authors/3/books/7, Params: { author_id: '3', id: '7' }

D URL: /books/7, Params: { author_id: '3', id: '7' }

💡 Hint

Nested resources include parent resource ID in URL and params with key named after parent resource.

Nested RESTful routes include the parent resource ID in the URL and params. For authors/3/books/7, params[:author_id] is '3' and params[:id] is '7'.

Practice

1. What does the resources :books line do in a Rails routes file?

easy

A. Creates all standard RESTful routes for the books resource automatically.

B. Creates only the index and show routes for books.

C. Creates a single custom route named books.

D. Deletes all routes related to books.

Solution

1. Step 1: Understand the resources method

   The resources method in Rails automatically generates all seven standard RESTful routes (index, show, new, create, edit, update, destroy) for a given resource.

2. Step 2: Apply to resources :books

   Using resources :books creates all these routes for the books controller, enabling standard CRUD actions.

3. Final Answer:

   Creates all standard RESTful routes for the books resource automatically. -> Option A

4. Quick Check:

   resources :books = all RESTful routes [OK]

Hint: Remember: resources creates all standard routes by default [OK]

Common Mistakes:

• Thinking it creates only some routes
• Confusing resources with resource (singular)
• Assuming it deletes routes

2. Which of the following is the correct syntax to create only the index and show routes for a resource named articles?

easy

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

B. resources :articles, except: [:index, :show]

C. resource :articles, only: [:index, :show]

D. resources :articles, only: index, show

Solution

1. Step 1: Use resources with only option

   To limit routes to specific actions, use only: [:index, :show] with resources.

2. Step 2: Check syntax correctness

   resources :articles, only: [:index, :show] correctly uses symbols in an array with only. resources :articles, except: [:index, :show] uses except which excludes actions, not includes. resource :articles, only: [:index, :show] uses singular resource which is for single objects, not collections. resources :articles, only: index, show syntax is invalid because only expects an array.

3. Final Answer:

   resources :articles, only: [:index, :show] -> Option A

4. Quick Check:

   Limit routes with only and array [OK]

Hint: Use only: with an array of symbols to limit routes [OK]

Common Mistakes:

• Using except instead of only
• Using singular resource for collections
• Incorrect syntax without brackets

3. Given the route declaration resources :users, except: [:destroy], which HTTP verb and path will NOT be available?

medium

A. GET /users/:id/edit

B. DELETE /users/:id

C. POST /users

D. GET /users

Solution

1. Step 1: Understand except: [:destroy]

   The except option removes the specified action routes. Here, destroy is excluded, so no route for deleting a user is created.

2. Step 2: Identify the HTTP verb and path for destroy

   The destroy action corresponds to the HTTP DELETE verb on the path /users/:id. This route will be missing.

3. Final Answer:

   DELETE /users/:id -> Option B

4. Quick Check:

   except: [:destroy] removes DELETE route [OK]

Hint: Destroy action uses DELETE verb; except removes it [OK]

Common Mistakes:

• Confusing except with only
• Thinking GET routes are removed
• Mixing HTTP verbs with wrong actions

4. Identify the error in this routes file snippet:

resources :products, only: :show, :edit

medium

A. The only option should list all seven RESTful actions.

B. The resources method cannot use only option.

C. The resource name products should be singular.

D. The only option should be an array of symbols, not separate symbols.

Solution

1. Step 1: Check syntax of only option

   The only option expects an array of symbols like only: [:show, :edit]. Writing only: :show, :edit passes :show as the only option and :edit is outside the hash, causing syntax error.

2. Step 2: Verify other options

   resources supports only. The resource name should be plural for collections. Listing all actions is optional.

3. Final Answer:

   The only option should be an array of symbols, not separate symbols. -> Option D

4. Quick Check:

   only needs array syntax [OK]

Hint: Use brackets for multiple actions in only: [:show, :edit] [OK]

Common Mistakes:

• Omitting brackets for multiple actions
• Using singular resource for collections
• Thinking only must list all actions

5. You want to create RESTful routes for a resource orders but only allow index, show, and create actions. Additionally, you want a custom member route cancel that responds to POST requests. Which routes file code is correct?

hard

A. resources :orders, except: [:edit, :update, :destroy] do\n post 'cancel', on: :member\nend

B. resources :orders, only: [:index, :show, :create] do\n get 'cancel', on: :collection\nend

C. resources :orders, only: [:index, :show, :create] do\n post 'cancel', on: :member\nend

D. resource :orders, only: [:index, :show, :create] do\n post 'cancel', on: :member\nend

Solution

1. Step 1: Limit routes to index, show, create

   Use only: [:index, :show, :create] to restrict routes to these actions.

2. Step 2: Add custom member route for cancel

   Use a block with post 'cancel', on: :member to add a POST route for cancel on individual orders.

3. Step 3: Check other options

   resources :orders, only: [:index, :show, :create] do\n get 'cancel', on: :collection\nend uses GET and collection which is incorrect for cancel on a single order. resources :orders, except: [:edit, :update, :destroy] do\n post 'cancel', on: :member\nend uses except which is less clear and includes extra routes. resource :orders, only: [:index, :show, :create] do\n post 'cancel', on: :member\nend uses singular resource which is wrong for collections.

4. Final Answer:

   resources :orders, only: [:index, :show, :create] do\n post 'cancel', on: :member\nend -> Option C

5. Quick Check:

   Use only with member block for custom POST route [OK]

Hint: Use member block with post for single resource custom action [OK]

Common Mistakes:

• Using collection instead of member for single resource
• Using singular resource for collections
• Using wrong HTTP verb for custom action