Nested resources in Rest API - Cheat Sheet & Quick Revision

Recall & Review

beginner

What are nested resources in REST APIs?

Nested resources are resources that exist within the context of another resource, showing a parent-child relationship in the URL structure.

beginner

Why use nested resources in REST API design?

They help organize related data clearly, making URLs more meaningful and showing how resources are connected, like comments belonging to a specific post.

beginner

Example of a nested resource URL for comments of a post with ID 5?

/posts/5/comments

intermediate

How does nesting resources affect HTTP methods like GET or POST?

HTTP methods operate on the nested resource within the parent context, for example, GET /posts/5/comments fetches comments for post 5, POST /posts/5/comments adds a comment to post 5.

intermediate

What is a potential downside of deeply nested resources?

Too many nested levels can make URLs long and complex, which can be hard to read and maintain. It's best to keep nesting shallow.

Which URL represents a nested resource for orders of a user with ID 10?

A /orders/users/10

B /orders/10/users

C /users/10/orders

D /users/orders/10

The correct nested resource URL places the parent resource first, then the child: /users/10/orders.

What HTTP method would you use to add a new comment to a post in a nested resource?

A GET

B POST

C DELETE

D PUT

POST is used to create or add new resources, such as a comment under a post.

Why might you avoid very deep nesting in REST API URLs?

A It can make URLs complex and hard to manage

B It improves security

C It makes URLs shorter

D It increases server speed

Deep nesting can make URLs long and complicated, which is hard to read and maintain.

Which of these is NOT a benefit of nested resources?

A Automatically improves database performance

B Makes URLs more meaningful

C Helps organize API endpoints logically

D Shows clear relationship between resources

Nested resources improve URL clarity but do not automatically improve database performance.

In the URL /books/3/chapters/7, what is the parent resource?

A 3

B chapters

C 7

D books

The parent resource is 'books' because chapters are nested inside a specific book.

Explain what nested resources are and give an example URL.

Think about how comments belong to posts in a blog.

Describe one advantage and one disadvantage of using nested resources in REST APIs.

Consider how URLs look and how easy they are to manage.

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