APIRouter for modular routes in FastAPI - Mini Project: Build & Apply

APIRouter for modular routes

📖 Scenario: You are building a simple web API for a bookstore. You want to organize your routes by grouping book-related routes separately from author-related routes.

🎯 Goal: Create a FastAPI app that uses APIRouter to modularize routes for books and authors, then include these routers in the main app.

📋 What You'll Learn

Create a FastAPI app instance named app

Create two APIRouter instances named book_router and author_router

Add a GET route /books/ to book_router that returns a list of book titles

Add a GET route /authors/ to author_router that returns a list of author names

Include both routers in the main app with prefixes /books and /authors respectively

💡 Why This Matters

🌍 Real World

Modular routes help organize large APIs by grouping related endpoints, making code easier to read and maintain.

💼 Career

Using APIRouter is a common practice in professional FastAPI projects to build scalable and clean APIs.

1

Create the FastAPI app and routers

Import FastAPI and APIRouter from fastapi. Create a FastAPI app instance called app. Create two APIRouter instances called book_router and author_router.

FastAPI

from fastapi import FastAPI, APIRouter

# Your code here

Need a hint?

Use app = FastAPI() to create the main app. Use book_router = APIRouter() and author_router = APIRouter() to create routers.

2

Add a GET route to book_router

Add a GET route / to book_router using the decorator @book_router.get("/"). Define a function get_books that returns the list ["The Hobbit", "1984", "Pride and Prejudice"].

FastAPI

from fastapi import FastAPI, APIRouter

app = FastAPI()
book_router = APIRouter()
author_router = APIRouter()

# Your code here

Need a hint?

Use @book_router.get("/") above a function named get_books that returns the list of book titles.

3

Add a GET route to author_router

Add a GET route / to author_router using the decorator @author_router.get("/"). Define a function get_authors that returns the list ["J.R.R. Tolkien", "George Orwell", "Jane Austen"].

FastAPI

from fastapi import FastAPI, APIRouter

app = FastAPI()
book_router = APIRouter()
author_router = APIRouter()

@book_router.get("/")
def get_books():
    return ["The Hobbit", "1984", "Pride and Prejudice"]

# Your code here

Need a hint?

Use @author_router.get("/") above a function named get_authors that returns the list of author names.

4

Include routers in the main app

Include book_router in app with prefix /books using app.include_router(book_router, prefix="/books"). Include author_router in app with prefix /authors using app.include_router(author_router, prefix="/authors").

FastAPI

from fastapi import FastAPI, APIRouter

app = FastAPI()
book_router = APIRouter()
author_router = APIRouter()

@book_router.get("/")
def get_books():
    return ["The Hobbit", "1984", "Pride and Prejudice"]

@author_router.get("/")
def get_authors():
    return ["J.R.R. Tolkien", "George Orwell", "Jane Austen"]

# Your code here

Need a hint?

Use app.include_router() to add both routers with their prefixes.