Async HTTP client calls in FastAPI - Mini Project: Build & Apply

Async HTTP Client Calls with FastAPI

📖 Scenario: You are building a FastAPI application that fetches data from an external API asynchronously. This helps your app stay fast and responsive, even when waiting for other servers.

🎯 Goal: Create a FastAPI app that uses an async HTTP client to get JSON data from a public API and returns it to the user.

📋 What You'll Learn

Use FastAPI to create a web server

Use the httpx.AsyncClient to make asynchronous HTTP GET requests

Create an endpoint /joke that fetches a random joke from the external API

Return the JSON response from the external API directly to the client

💡 Why This Matters

🌍 Real World

Many web apps need to get data from other servers without freezing or slowing down. Async HTTP clients let your app stay fast and handle many users at once.

💼 Career

Knowing how to use async HTTP calls in FastAPI is important for backend developers building scalable APIs and microservices.

1

Set up FastAPI app and import httpx

Create a FastAPI app by importing FastAPI and httpx. Then create an instance called app.

FastAPI

from fastapi import FastAPI
import httpx

# Create FastAPI app instance
# Your code here

Need a hint?

Use app = FastAPI() to create the app instance.

2

Define the external API URL

Create a variable called joke_api_url and set it to the string "https://official-joke-api.appspot.com/random_joke".

FastAPI

from fastapi import FastAPI
import httpx

app = FastAPI()

# Define the external joke API URL
# Your code here

Need a hint?

Assign the URL string exactly to joke_api_url.

3

Create async endpoint to fetch joke

Define an async function called get_joke with the route decorator @app.get("/joke"). Inside, use async with httpx.AsyncClient() as client to make a GET request to joke_api_url. Await the response and return response.json().

FastAPI

from fastapi import FastAPI
import httpx

app = FastAPI()

joke_api_url = "https://official-joke-api.appspot.com/random_joke"

# Create async endpoint to fetch joke
# Your code here

Need a hint?

Remember to use async def and await for the HTTP call.

4

Add main guard to run app with Uvicorn

Add the code block if __name__ == "__main__": and inside it call import uvicorn and then uvicorn.run(app, host="127.0.0.1", port=8000) to run the FastAPI app.

FastAPI

from fastapi import FastAPI
import httpx

app = FastAPI()

joke_api_url = "https://official-joke-api.appspot.com/random_joke"

@app.get("/joke")
async def get_joke():
    async with httpx.AsyncClient() as client:
        response = await client.get(joke_api_url)
        return response.json()

# Add main guard to run app with uvicorn
# Your code here

Need a hint?

This lets you run the app by executing the script directly.