Trailing slash behavior in FastAPI - Mini Project: Build & Apply

Trailing slash behavior

📖 Scenario: You are building a simple web API using FastAPI. You want to understand how FastAPI handles URLs with and without trailing slashes.

🎯 Goal: Create two API endpoints: one with a trailing slash and one without. Observe how FastAPI responds to requests to these endpoints with and without trailing slashes.

📋 What You'll Learn

Create a FastAPI app instance named app

Create a GET endpoint at /items/ (with trailing slash) that returns a JSON message

Create a GET endpoint at /users (without trailing slash) that returns a JSON message

Use the exact function names read_items and read_users for the endpoints

💡 Why This Matters

🌍 Real World

Web APIs often have URLs with or without trailing slashes. Understanding how your framework handles these helps avoid broken links or unexpected redirects.

💼 Career

Backend developers must know how to define routes correctly and handle URL patterns to build reliable APIs.

1

Create FastAPI app instance

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

FastAPI

from fastapi import FastAPI

# Create FastAPI app instance
# Your code here

Need a hint?

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

2

Add GET endpoint with trailing slash

Add a GET endpoint at /items/ (with trailing slash) using @app.get("/items/"). Define a function called read_items that returns {"message": "Items endpoint with slash"}.

FastAPI

from fastapi import FastAPI

app = FastAPI()

# Add GET endpoint at /items/ with trailing slash
# Your code here

Need a hint?

Use @app.get("/items/") decorator and define read_items function.

3

Add GET endpoint without trailing slash

Add a GET endpoint at /users (without trailing slash) using @app.get("/users"). Define a function called read_users that returns {"message": "Users endpoint without slash"}.

FastAPI

from fastapi import FastAPI

app = FastAPI()

@app.get("/items/")
def read_items():
    return {"message": "Items endpoint with slash"}

# Add GET endpoint at /users without trailing slash
# Your code here

Need a hint?

Use @app.get("/users") decorator and define read_users function.

4

Add root endpoint to test trailing slash behavior

Add a GET endpoint at / using @app.get("/"). Define a function called read_root that returns {"message": "Root endpoint"}. This helps test how FastAPI handles root URL with or without slash.

FastAPI

from fastapi import FastAPI

app = FastAPI()

@app.get("/items/")
def read_items():
    return {"message": "Items endpoint with slash"}

@app.get("/users")
def read_users():
    return {"message": "Users endpoint without slash"}

# Add GET endpoint at / (root)
# Your code here

Need a hint?

Use @app.get("/") decorator and define read_root function.