Hierarchical resource paths in Rest API

Introduction

Hierarchical resource paths help organize and access related data in a clear, logical way. They show how resources connect like folders in a file system.

When you want to access a specific item inside a collection, like a single book in a library.

When you need to show relationships, such as comments belonging to a blog post.

When designing APIs that reflect real-world nested data, like users and their orders.

When you want URLs that are easy to read and understand by humans.

When you want to keep your API organized and scalable as it grows.

Syntax

Rest API

/resource1/{id1}/resource2/{id2}/resource3

Each part separated by slashes represents a level in the hierarchy.

Curly braces {} show variable parts, like IDs.

Examples

Access order 456 that belongs to user 123.

Rest API

/users/123/orders/456

Get book 42 inside library 5.

Rest API

/libraries/5/books/42

List all employees in department 3 of company 7.

Rest API

/companies/7/departments/3/employees

Sample Program

This example shows a hierarchical path to get a specific comment. It starts from the user, then the post, then the comment.

Rest API

GET /users/42/posts/10/comments/5

# This request fetches comment 5 on post 10 by user 42.

Important Notes

Keep paths simple and consistent for easier use.

Use nouns for resources, not verbs.

Hierarchical paths help with permissions and filtering data logically.

Summary

Hierarchical resource paths organize data like folders inside folders.

They use slashes and IDs to show relationships clearly.

This makes APIs easier to understand and use.

Practice

1. What does a hierarchical resource path in a REST API represent?

easy

A. A nested structure showing relationships between resources

B. A random list of unrelated resources

C. A single resource without any relation

D. A method to encrypt API data

Solution

1. Step 1: Understand resource organization

   Hierarchical paths show how resources are connected, like folders inside folders.

2. Step 2: Identify the purpose of hierarchical paths

   They help represent parent-child relationships clearly in the API URL.

3. Final Answer:

   A nested structure showing relationships between resources -> Option A

4. Quick Check:

   Hierarchical paths = nested resource relationships [OK]

Hint: Think of folders inside folders to understand hierarchy [OK]

Common Mistakes:

• Confusing hierarchy with unrelated resource lists
• Ignoring the relationship between resources
• Thinking it's about data encryption

2. Which of the following is the correct syntax for a hierarchical resource path to access comments of a post with ID 10?

easy

A. /posts/10/comments

B. /comments/posts/10

C. /posts/comments/10

D. /10/posts/comments

Solution

1. Step 1: Identify the parent resource and its ID

   The parent resource is 'posts' with ID 10, so it comes first in the path.

2. Step 2: Append the child resource

   Comments belong to the post, so '/comments' follows '/posts/10'.

3. Final Answer:

   /posts/10/comments -> Option A

4. Quick Check:

   Parent resource + ID + child resource = /posts/10/comments [OK]

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

Common Mistakes:

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

3. Given the REST API path /users/5/orders/12/items, what resource does this path represent?

medium

A. All orders of all users

B. Order 12 of user 5

C. User 5's profile information

D. Items in order 12 of user 5

Solution

1. Step 1: Break down the path segments

   /users/5 means user with ID 5, /orders/12 means order with ID 12 for that user, and /items means the items in that order.

2. Step 2: Understand the full resource

   The path points to the items inside order 12 which belongs to user 5.

3. Final Answer:

   Items in order 12 of user 5 -> Option D

4. Quick Check:

   Path shows nested resources = items in order 12 of user 5 [OK]

Hint: Read path left to right as parent to child resources [OK]

Common Mistakes:

• Ignoring the nested order and item relationship
• Confusing order with user profile
• Assuming it lists all users or orders

4. Identify the error in this hierarchical REST API path: /projects//tasks/7

medium

A. Missing task ID before 7

B. Double slash between 'projects' and 'tasks' is invalid

C. Resource names should be capitalized

D. The path should end with a slash

Solution

1. Step 1: Check the path syntax

   The path has two slashes '//' between 'projects' and 'tasks', which is not valid in REST API paths.

2. Step 2: Understand correct path format

   Only one slash should separate resource names and IDs to maintain proper hierarchy.

3. Final Answer:

   Double slash between 'projects' and 'tasks' is invalid -> Option B

4. Quick Check:

   Only single slashes separate path segments [OK]

Hint: Check for extra or missing slashes in paths [OK]

Common Mistakes:

• Ignoring double slashes as harmless
• Thinking resource names must be capitalized
• Believing trailing slash is mandatory

5. You want to design a REST API path to access all reviews for a specific product variant. The product ID is 20 and the variant ID is 5. Which path correctly represents this hierarchical resource?

hard

A. /products/reviews/20/variants/5

B. /reviews/products/20/variants/5

C. /products/20/variants/5/reviews

D. /variants/5/products/20/reviews

Solution

1. Step 1: Identify the resource hierarchy

   Reviews belong to a variant, which belongs to a product. So the path should start with product ID, then variant ID, then reviews.

2. Step 2: Construct the path in correct order

   The correct order is /products/20/variants/5/reviews to show this nested relationship clearly.

3. Final Answer:

   /products/20/variants/5/reviews -> Option C

4. Quick Check:

   Parent to child order: product -> variant -> reviews [OK]

Hint: Order path segments from general to specific resource [OK]

Common Mistakes:

• Placing reviews before products or variants
• Mixing order of product and variant IDs
• Using unrelated resource order