Async path operations in FastAPI - Mini Project: Build & Apply

Async Path Operations with FastAPI

📖 Scenario: You are building a simple web API using FastAPI to handle user data asynchronously. This API will have endpoints to get user information and add new users without blocking the server.

🎯 Goal: Create a FastAPI app with asynchronous path operations to get a list of users and add a new user asynchronously.

📋 What You'll Learn

Create a FastAPI app instance named app

Create an initial list called users with two user names: 'alice' and 'bob'

Add a configuration variable max_users set to 5

Create an async GET path operation at /users that returns the users list

Create an async POST path operation at /users that accepts a username string and adds it to users if the list length is less than max_users

💡 Why This Matters

🌍 Real World

APIs often need to handle multiple requests at the same time without waiting. Using async path operations in FastAPI helps build fast and scalable web services.

💼 Career

Understanding async path operations is essential for backend developers working with modern Python web frameworks like FastAPI to build efficient APIs.

1

Create initial data and FastAPI app

Create a FastAPI app instance called app and a list called users with the exact entries 'alice' and 'bob'.

FastAPI

from fastapi import FastAPI

# Create FastAPI app instance and initial users list
# Your code here

Need a hint?

Use app = FastAPI() to create the app and assign the list ['alice', 'bob'] to users.

2

Add configuration variable

Add a variable called max_users and set it to the integer 5.

FastAPI

from fastapi import FastAPI

app = FastAPI()

users = ['alice', 'bob']

# Add max_users variable here
# Your code here

Need a hint?

Simply write max_users = 5 below the users list.

3

Create async GET path operation

Create an async GET path operation at /users using the decorator @app.get("/users"). Define an async function called get_users that returns the users list.

FastAPI

from fastapi import FastAPI

app = FastAPI()

users = ['alice', 'bob']

max_users = 5

# Create async GET path operation for /users
# Your code here

Need a hint?

Use @app.get("/users") decorator and define async def get_users(): that returns users.

4

Create async POST path operation to add user

Create an async POST path operation at /users using @app.post("/users"). Define an async function called add_user that accepts a parameter username: str. Inside the function, check if the length of users is less than max_users. If yes, append username to users and return a dictionary {"message": "User added"}. Otherwise, return {"message": "User limit reached"}.

FastAPI

from fastapi import FastAPI

app = FastAPI()

users = ['alice', 'bob']

max_users = 5

@app.get("/users")
async def get_users():
    return users

# Create async POST path operation to add a user
# Your code here

Need a hint?

Use @app.post("/users") and define async def add_user(username: str):. Check the length of users and append if below max_users.