README.md

Module 7: Advanced API Design

Getting Started

1. Create a virtual environment:

   python -m venv .venv

   Activate the virtual environment:

   • On macOS/Linux:

   source .venv/bin/activate  

   • On Windows use .venv\Scripts\activate

Install Dependencies

pip install fastapi uvicorn slowapi python-multipart

Run the Application

uvicorn main:app --reload

Practical Exercises: Advanced API Design in FastAPI

✅ Exercise 1: Implement a Product catalog

models/product.py

• Objectice: Implement a simple product catalog system in Python. The catalog should store different products (such as books and fruits) and allow you to work with them in a structured way.

• Create a Product class with the following:

• Attributes: id (integer, unique identifier for the product) name (string, name of the product) price (float, price of the product) description (string, optional description of the product)

• A __repr__ method so products can be printed in a readable way.

• A to_dict method that returns a dictionary representation of the product.

• Create an initial list of items containing three books. Each book should have: id, a descriptive name, a price, a description

• Implement a function fill_items_list() that adds:

  • Books with IDs from 4 to 50, each named "Book with title: Book ", priced at 20.0 + id.
  • Fruits with IDs from 51 to 100, each named "Fruit: Fruit ", priced at 1.0 + id.

✅ Exercise 2: Implement API versioning

routers/products_v1.py, routers/products_v2.py

• Objective: Create two versions of a simple product API:

• Instructions:

  • Create an /api/v1/products/ endpoint that returns a list of product names.
  • Create an /api/v2/products/ endpoint that returns product names and prices.

• Test that both endpoints work independently.

✅ Exercise 3: Add pagination, filtering, and sorting

routers/products_v1.py

• Objective: Enhance the api/v1/products/ endpoint.
• Instructions:
  • Create an endpoint `/products/ that supports:
    • skip and limit query parameters
    • filtering by category (e.g., /products/?category=books)
    • sorting by price or name (order_by param)

HINT: Use an in-memory list or dummy database.

• Bonus:
  • Add support for descending sort via order_dir=desc.

✅ Exercise 4: Apply rate limiting

main.py

• Objective: Limit request frequency to sensitive routes.

• Instructions:

  • Install and configure slowapi.
  • Create a route /login/ and apply a rate limit of 5 requests per minute per IP.
  • Return a custom error message when the limit is exceeded.

• Bonus:

  • Apply different limits to authenticated vs unauthenticated users.

✅ Exercise 5: Schedule background tasks

main.py

• Objective: Offload non-blocking tasks using BackgroundTasks.

• Instructions:

  • Create a POST route /send-email/ that accepts an email address.
  • Simulate email sending with a background task that logs the address to a file.
  • Return immediately with a success message.

• Bonus:

  • Add another background task to notify an admin after email is sent.

✅ Exercise 6: Add caching to expensive operations

main.py

• Objective: Cache expensive or frequently called endpoints.

• Instructions:

  • Create an endpoint /stats/ that simulates a slow operation (e.g., sleep for 3s).

  • Use lru_cache to cache the result for repeated calls.

  • Return the same result instantly for subsequent calls.

• Bonus:

  • Replace lru_cache with Redis-based caching using aioredis.
  • Add cache invalidation via a /refresh-stats/ endpoint.