Nested routes in Ruby on Rails - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a nested route for comments inside posts.

Ruby on Rails

resources :posts do
  [1] :comments
end

Drag options to blanks, or click blank then click option'

Aresources

Bresource

Cmember

Dcollection

Attempts:

3 left

💡 Hint

Common Mistakes

Using resource instead of resources for nested routes.

Using member or collection which are for different purposes.

Use resources to define nested routes for multiple comments under posts.

2fill in blank

medium

Complete the code to add a nested route for reviews inside products with only the index action.

Ruby on Rails

resources :products do
  resources :reviews, only: [:[1]]
end

Drag options to blanks, or click blank then click option'

Acreate

Bshow

Cindex, :show

Dindex

Attempts:

3 left

💡 Hint

Common Mistakes

Putting multiple actions as a single string instead of an array.

Using actions not allowed by the only option.

The only option expects an array of symbols. Here, [:index] limits routes to the index action only.

3fill in blank

hard

Fix the error in the nested route to correctly nest photos inside galleries.

Ruby on Rails

resources :galleries do
  [1] :photos
end

Drag options to blanks, or click blank then click option'

Amember

Bresources

Cresource

Dcollection

Attempts:

3 left

💡 Hint

Common Mistakes

Using resource which creates singular routes.

Using member or collection incorrectly.

Use resources to nest multiple photos inside galleries. resource is for singular resources.

4fill in blank

hard

Fill both blanks to create nested routes for chapters inside books with only show and index actions.

Ruby on Rails

resources :books do
  resources :chapters, only: [:[1], :[2]]
end

Drag options to blanks, or click blank then click option'

Ashow

Bindex

Cedit

Dnew

Attempts:

3 left

💡 Hint

Common Mistakes

Using actions like edit or new which are not requested.

Mixing up the order of actions.

The nested chapters routes are limited to index and show actions using the only option.

5fill in blank

hard

Fill all three blanks to define nested routes for comments inside articles with only create, destroy, and update actions.

Ruby on Rails

resources :articles do
  resources :comments, only: [:[1], :[2], :[3]]
end

Drag options to blanks, or click blank then click option'

Acreate

Bdestroy

Cupdate

Dshow

Attempts:

3 left

💡 Hint

Common Mistakes

Including show when it is not requested.

Missing the update action.

The nested comments routes are limited to create, destroy, and update actions using the only option.

Practice

1. What is the main purpose of using nested routes in a Rails application?

easy

A. To speed up database queries automatically

B. To group related resources and show their connection in URLs

C. To create routes without controllers

D. To avoid using RESTful conventions

Solution

1. Step 1: Understand nested routes concept

   Nested routes group related resources in URLs to reflect their relationship, like a parent and its children.

2. Step 2: Identify the purpose in URL structure

   This grouping helps keep URLs organized and meaningful, showing the connection between resources.

3. Final Answer:

   To group related resources and show their connection in URLs -> Option B

4. Quick Check:

   Nested routes = Group related resources [OK]

Hint: Nested routes show parent-child URL relationships clearly [OK]

Common Mistakes:

• Thinking nested routes speed up queries
• Believing nested routes remove need for controllers
• Assuming nested routes ignore RESTful design

2. Which of the following is the correct syntax to define a nested route for comments inside posts in Rails?

easy

A. resources :comments do
resources :posts
end

B. resource :posts, :comments

C. resources :posts do
resources :comments
end

D. resources :posts, nested: :comments

Solution

1. Step 1: Recall nested route syntax

   In Rails, nested routes are defined by placing resources :child inside a block of resources :parent.

2. Step 2: Match syntax to example

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

3. Final Answer:

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

4. Quick Check:

   Nested routes syntax = block inside parent resource [OK]

Hint: Use block syntax: parent do child end [OK]

Common Mistakes:

• Reversing parent and child resources
• Using commas instead of blocks
• Using singular resource instead of plural

3. Given the nested routes below, what is the URL helper for editing a comment with ID 5 belonging to post with ID 3?

resources :posts do
  resources :comments
end

medium

A. edit_post_comment_path(3, 5)

B. edit_comment_path(5)

C. edit_post_path(3, 5)

D. edit_comments_post_path(5, 3)

Solution

1. Step 1: Understand nested URL helpers

   For nested routes, the helper includes both parent and child resource names and IDs, like edit_post_comment_path(post_id, comment_id).

2. Step 2: Match IDs to parameters

   Post ID is 3, comment ID is 5, so the helper is edit_post_comment_path(3, 5).

3. Final Answer:

   edit_post_comment_path(3, 5) -> Option A

4. Quick Check:

   Nested helper = edit_parent_child_path(parent_id, child_id) [OK]

Hint: Nested helpers need parent ID first, then child ID [OK]

Common Mistakes:

• Using only child ID in helper
• Swapping parent and child IDs
• Using plural instead of singular in helper

4. Identify the error in the following nested routes definition:

resources :authors do
  resources :books
resources :publishers
end

medium

A. Should use resource instead of resources for books

B. Cannot nest resources :publishers inside resources :authors

C. No error, syntax is correct

D. Missing end for the resources :authors block

Solution

1. Step 1: Check block structure

   The resources :authors block opens but does not close before defining resources :publishers.

2. Step 2: Confirm correct nesting

   Each block must have a matching end. Here, resources :publishers is outside the intended block but inside the authors block without closure.

3. Final Answer:

   Missing end for the resources :authors block -> Option D

4. Quick Check:

   Every block needs matching end [OK]

Hint: Count your do/end pairs carefully [OK]

Common Mistakes:

• Forgetting to close blocks with end
• Nesting unrelated resources incorrectly
• Confusing singular and plural resource keywords

5. You want to create nested routes for projects and their tasks, but only allow index and show actions for tasks. Which is the correct way to define this in Rails?

hard

A. resources :projects do
resources :tasks, only: [:index, :show]
end

B. resources :projects do
resources :tasks, except: [:index, :show]
end

C. resources :projects, only: [:index, :show] do
resources :tasks
end

D. resources :projects do
resource :tasks, only: [:index, :show]
end

Solution

1. Step 1: Use nested resources with action limits

   To limit actions on nested resources, use only: [:index, :show] inside the nested resources block.

2. Step 2: Verify correct syntax

   resources :projects do resources :tasks, only: [:index, :show] end correctly nests tasks inside projects and limits actions to index and show.

3. Final Answer:

   resources :projects do resources :tasks, only: [:index, :show] end -> Option A

4. Quick Check:

   Limit nested actions with only: [OK]

Hint: Use only: to limit nested resource actions [OK]

Common Mistakes:

• Using except instead of only
• Limiting actions on parent instead of child
• Using singular resource for multiple tasks