Nested resources in Rest API - Mini Project: Build & Apply

Nested Resources in a REST API

📖 Scenario: You are building a simple REST API for a blog. Each blog has many posts. You want to organize your API so that posts are nested inside blogs. This means the URL for posts will include the blog they belong to, like /blogs/1/posts.

🎯 Goal: Create a basic REST API with nested resources where posts belong to blogs. You will define the data, set up a route prefix for blogs, create a nested route for posts inside blogs, and finally show how to get all posts for a specific blog.

📋 What You'll Learn

Create a dictionary called blogs with two blogs, each having an id and name.

Create a list called posts with posts that include id, blog_id, and title.

Define a variable blog_id to select which blog's posts to get.

Write a function get_posts_for_blog(blog_id) that returns posts belonging to the given blog.

Print the titles of posts for the selected blog.

💡 Why This Matters

🌍 Real World

Nested resources are common in REST APIs to organize related data clearly, like posts inside blogs or comments inside posts.

💼 Career

Understanding nested resources helps you design clean and scalable APIs, a key skill for backend developers and API designers.

1

Create the initial data structures

Create a dictionary called blogs with these exact entries: 1: {'id': 1, 'name': 'Tech Blog'} and 2: {'id': 2, 'name': 'Food Blog'}. Also create a list called posts with these exact dictionaries: {'id': 1, 'blog_id': 1, 'title': 'New Python Features'}, {'id': 2, 'blog_id': 1, 'title': 'REST API Tips'}, and {'id': 3, 'blog_id': 2, 'title': 'Best Pizza Recipes'}.

Rest API

# Create the blogs dictionary and posts list
# Your code here

Hint

Think of blogs as a dictionary where keys are blog IDs and values are blog details. posts is a list of dictionaries, each with a blog ID to show which blog it belongs to.

2

Set the blog ID to filter posts

Create a variable called blog_id and set it to 1 to select the Tech Blog.

Rest API

blogs = {
    1: {'id': 1, 'name': 'Tech Blog'},
    2: {'id': 2, 'name': 'Food Blog'}
}

posts = [
    {'id': 1, 'blog_id': 1, 'title': 'New Python Features'},
    {'id': 2, 'blog_id': 1, 'title': 'REST API Tips'},
    {'id': 3, 'blog_id': 2, 'title': 'Best Pizza Recipes'}
]

# Set the blog_id to 1
# Your code here

Hint

This variable will help us get posts only for the selected blog.

3

Create a function to get posts for a blog

Write a function called get_posts_for_blog(blog_id) that returns a list of posts from posts where the post's blog_id matches the function's blog_id parameter.

Rest API

blogs = {
    1: {'id': 1, 'name': 'Tech Blog'},
    2: {'id': 2, 'name': 'Food Blog'}
}

posts = [
    {'id': 1, 'blog_id': 1, 'title': 'New Python Features'},
    {'id': 2, 'blog_id': 1, 'title': 'REST API Tips'},
    {'id': 3, 'blog_id': 2, 'title': 'Best Pizza Recipes'}
]

blog_id = 1

# Define get_posts_for_blog function
# Your code here

Hint

Use a list comprehension to filter posts where post['blog_id'] equals the function's blog_id parameter.

4

Print the titles of posts for the selected blog

Use the function get_posts_for_blog(blog_id) to get posts for the blog with blog_id. Then print each post's title on its own line.

Rest API

blogs = {
    1: {'id': 1, 'name': 'Tech Blog'},
    2: {'id': 2, 'name': 'Food Blog'}
}

posts = [
    {'id': 1, 'blog_id': 1, 'title': 'New Python Features'},
    {'id': 2, 'blog_id': 1, 'title': 'REST API Tips'},
    {'id': 3, 'blog_id': 2, 'title': 'Best Pizza Recipes'}
]

blog_id = 1

def get_posts_for_blog(blog_id):
    return [post for post in posts if post['blog_id'] == blog_id]

# Print the titles of posts for the selected blog
# Your code here

Hint

Call the function with blog_id and loop over the returned posts to print each title.

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