Sending and receiving messages in FastAPI - Mini Project: Build & Apply

Sending and receiving messages

📖 Scenario: You are building a simple messaging API where users can send and receive messages. This API will allow clients to post new messages and get all messages sent so far.

🎯 Goal: Create a FastAPI app that stores messages in memory, allows adding new messages via POST, and retrieving all messages via GET.

📋 What You'll Learn

Create a list called messages to store message strings

Create a FastAPI app instance called app

Add a POST endpoint /send that accepts a JSON body with a content field and appends it to messages

Add a GET endpoint /receive that returns all stored messages as JSON

💡 Why This Matters

🌍 Real World

Messaging APIs are common in chat apps, notifications, and communication platforms.

💼 Career

Understanding how to build simple REST APIs with FastAPI is useful for backend development roles.

1

Data setup: Create the messages list

Create a list called messages that is initially empty to store message strings.

FastAPI

# Create an empty list called messages
# Your code here

Need a hint?

Use messages = [] to create an empty list.

2

Configuration: Create the FastAPI app instance

Import FastAPI from fastapi and create an app instance called app.

FastAPI

messages = []
# Import FastAPI and create app instance
# Your code here

Need a hint?

Use from fastapi import FastAPI and then app = FastAPI().

3

Core logic: Add POST endpoint to send messages

Add a POST endpoint /send to app that accepts a JSON body with a content field and appends it to the messages list. Use a function named send_message with a parameter message of type dict.

FastAPI

from fastapi import FastAPI

messages = []
app = FastAPI()

# Add POST endpoint /send to append message content
# Your code here

Need a hint?

Use @app.post("/send") decorator and an async function that appends message["content"] to messages.

4

Completion: Add GET endpoint to receive all messages

Add a GET endpoint /receive to app that returns the entire messages list as JSON. Use a function named receive_messages.

FastAPI

from fastapi import FastAPI

messages = []
app = FastAPI()

@app.post("/send")
async def send_message(message: dict):
    messages.append(message["content"])
    return {"status": "Message received"}

# Add GET endpoint /receive to return all messages
# Your code here

Need a hint?

Use @app.get("/receive") decorator and return {"messages": messages}.