Nested resources in Rest API - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a nested route for comments under posts in a REST API.

Rest API

app.route('/posts/[1]/comments')

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

A<postId>

BpostId

C{postId}

D:postId

Attempts:

3 left

💡 Hint

Common Mistakes

Using curly braces or angle brackets instead of colon for URL parameters.

Omitting the colon before the parameter name.

In REST API routing, parameters in the URL path are defined with a colon prefix, like ':postId'.

2fill in blank

medium

Complete the code to extract the post ID from the request parameters in a nested route handler.

Rest API

const postId = req.params.[1];

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

ApostID

BpostId

Cpost_id

Did

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different parameter name than defined in the route.

Using underscores or different casing.

The parameter name in the URL is 'postId', so we access it as req.params.postId.

3fill in blank

hard

Fix the error in the nested route path to correctly define a route for a specific comment under a post.

Rest API

app.get('/posts/:postId/comments/[1]', (req, res) => { /* handler */ });

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

A:commentId

B{commentId}

CcommentId

D<commentId>

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting the colon before the parameter name.

Using curly braces or angle brackets instead of colon.

Route parameters must be prefixed with a colon ':' to be recognized as variables.

4fill in blank

hard

Fill both blanks to create a nested route that handles updating a comment for a specific post.

Rest API

app.[1]('/posts/:postId/comments/:commentId', (req, res) => {
  const postId = req.params.[2];
  // update logic
});

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

Aput

BpostId

Cpatch

DcommentId

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'get' or 'post' instead of 'put' or 'patch' for updates.

Accessing the wrong parameter name.

Use HTTP PUT method for updating, and access the postId parameter from req.params.

5fill in blank

hard

Fill all three blanks to define a nested DELETE route for removing a comment from a post.

Rest API

app.[1]('/posts/:[2]/comments/:[3]', (req, res) => {
  const postId = req.params.[2];
  const commentId = req.params.[3];
  // delete logic
});

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

Adelete

BpostId

CcommentId

Dremove

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'remove' instead of 'delete' as HTTP method.

Mismatching parameter names between URL and req.params.

Use the DELETE method and access both postId and commentId parameters to identify the resource to delete.

Practice

1. What is the main purpose of using nested resources in a REST API?

easy

A. To make URLs shorter and simpler

B. To show how one resource belongs inside another resource

C. To avoid using IDs in URLs

D. To separate unrelated data into different APIs

Solution

1. Step 1: Understand nested resources concept

   Nested resources organize data by showing relationships, like a comment inside a post.

2. Step 2: Identify the purpose of nesting

   Nesting clarifies that one resource belongs to another, helping API users find related data easily.

3. Final Answer:

   To show how one resource belongs inside another resource -> Option B

4. Quick Check:

   Nested resources = parent-child relationship [OK]

Hint: Nested URLs show parent-child links clearly [OK]

Common Mistakes:

• Thinking nested resources make URLs shorter
• Believing IDs are not needed in nested URLs
• Confusing unrelated data separation with nesting

2. Which of the following is the correct nested URL format to get comments of a post with ID 5?

easy

A. /comments/5/posts

B. /comments/posts/5

C. /posts/5/comments

D. /posts/comments/5

Solution

1. Step 1: Identify parent and child in URL

   The parent is 'posts' with ID 5, and the child is 'comments'. The child comes after the parent.

2. Step 2: Check URL structure

   The correct format is /parent/{parent_id}/child, so /posts/5/comments is correct.

3. Final Answer:

   /posts/5/comments -> Option C

4. Quick Check:

   Parent ID before child resource [OK]

Hint: Parent resource and ID come before child resource in URL [OK]

Common Mistakes:

• Placing child resource before parent
• Swapping IDs and resource names
• Using incorrect order of URL segments

3. Given the nested URL /users/10/orders/3, what resource does this URL represent?

medium

A. Order with ID 3 belonging to user with ID 10

B. User with ID 3 who placed order 10

C. All orders of user 10 and order 3 combined

D. User 10's profile and order 3 details merged

Solution

1. Step 1: Analyze URL segments

   The URL shows 'users' with ID 10, then 'orders' with ID 3 nested inside.

2. Step 2: Understand resource relationship

   This means order 3 belongs to user 10, so the URL points to that specific order.

3. Final Answer:

   Order with ID 3 belonging to user with ID 10 -> Option A

4. Quick Check:

   Nested resource = child inside parent [OK]

Hint: Read URL left to right: parent then child with IDs [OK]

Common Mistakes:

• Mixing up which ID belongs to user or order
• Thinking URL shows combined or merged data
• Ignoring the order of resources in URL

4. You have this nested route defined: /projects/{projectId}/tasks/{taskId}. Which URL is incorrect to get task 7 of project 2?

medium

A. /projects/2/tasks/7/

B. /projects/2/tasks/7

C. /projects/2/tasks/07

D. /tasks/7/projects/2

Solution

1. Step 1: Check correct nested URL format

   The correct format is /projects/{projectId}/tasks/{taskId}, so project ID comes before task ID.

2. Step 2: Identify incorrect URL

   /tasks/7/projects/2 reverses the order to /tasks/7/projects/2, which breaks nesting rules.

3. Final Answer:

   /tasks/7/projects/2 -> Option D

4. Quick Check:

   Parent resource must come before child in URL [OK]

Hint: Parent resource always precedes child resource in nested URLs [OK]

Common Mistakes:

• Swapping parent and child in URL
• Adding trailing slashes incorrectly
• Using leading zeros in IDs (usually allowed but check API)

5. You want to design a REST API for a blog where each post has multiple comments, and each comment can have multiple replies. Which nested URL correctly accesses reply 4 of comment 2 on post 10?

hard

A. /posts/10/comments/2/replies/4

B. /posts/10/replies/4/comments/2

C. /comments/2/posts/10/replies/4

D. /posts/10/comments/replies/4/2

Solution

1. Step 1: Understand the resource hierarchy

   Post is the top parent, comments belong to posts, and replies belong to comments.

2. Step 2: Build nested URL from parent to child

   The URL should list post ID, then comment ID, then reply ID in order: /posts/10/comments/2/replies/4.

3. Final Answer:

   /posts/10/comments/2/replies/4 -> Option A

4. Quick Check:

   Nested URL = parent -> child -> grandchild [OK]

Hint: List resources from top parent to deepest child in URL [OK]

Common Mistakes:

• Mixing order of nested resources
• Skipping intermediate resource IDs
• Placing child before parent in URL