Folder structure patterns in FastAPI - Mini Project: Build & Apply

Folder Structure Patterns in FastAPI

📖 Scenario: You are building a simple FastAPI web application to manage books in a library. To keep your project clean and easy to maintain, you want to organize your code using a common folder structure pattern.

🎯 Goal: Build a basic FastAPI project with a clear folder structure that separates the main app, routers, and models.

📋 What You'll Learn

Create a main application file main.py inside the app folder

Create a routers folder inside app with a books.py router file

Create a models.py file inside app for data models

Include a simple route in books.py that returns a list of book titles

💡 Why This Matters

🌍 Real World

Organizing code in folders is essential for real FastAPI projects to keep code manageable and scalable.

💼 Career

Understanding folder structure patterns is a key skill for backend developers working with FastAPI or similar frameworks.

1

Create the initial folder structure and main app file

Create a folder called app. Inside app, create a file named main.py with the following code: import FastAPI from fastapi and create an instance called app.

FastAPI

# Create the app folder and main.py file
from fastapi import FastAPI

app = FastAPI()
# Your code here

Need a hint?

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

2

Add a routers folder and create books router

Inside the app folder, create a folder named routers. Inside routers, create a file called books.py. In books.py, import APIRouter from fastapi, create a router instance called router, and add a GET route /books that returns a list of book titles: ["Book A", "Book B"].

FastAPI

from fastapi import FastAPI

app = FastAPI()

# In routers/books.py
from fastapi import APIRouter

router = APIRouter()

# Your code here

Need a hint?

Create router = APIRouter() and add a GET route @router.get("/books") that returns the list.

3

Create a models.py file for data models

Inside the app folder, create a file named models.py. In this file, import BaseModel from pydantic and create a class Book that inherits from BaseModel with two fields: title (string) and author (string).

FastAPI

# routers/books.py
from fastapi import APIRouter

router = APIRouter()

@router.get("/books")
async def get_books():
    return ["Book A", "Book B"]

# In models.py
from pydantic import BaseModel

# Your code here

Need a hint?

Use class Book(BaseModel): with title: str and author: str fields.

4

Connect the books router in main.py

In main.py, import router from app.routers.books and include it in the app using app.include_router(router).

FastAPI

from fastapi import FastAPI
from app.routers.books import router

app = FastAPI()

# Your code here to include the router

Need a hint?

Use app.include_router(router) to add the books routes to the main app.