Building a REST API with FastAPI

FastAPI is one of the fastest Python web frameworks, and its developer experience is outstanding. Here's how I approach building APIs with it.

Why FastAPI?

Automatic OpenAPI docs - Swagger UI out of the box

Type hints - native Python typing for validation

Async support - built for async/await from the start

Pydantic - powerful data validation

Basic setup

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()

class Item(BaseModel):
    name: str
    price: float

@app.post("/items/")
async def create_item(item: Item):
    return {"name": item.name, "price": item.price}

Dependency injection

FastAPI's dependency injection system is elegant for things like auth:

from fastapi import Depends, HTTPException

async def get_current_user(token: str):
    user = verify_token(token)
    if not user:
        raise HTTPException(status_code=401)
    return user

@app.get("/me")
async def read_me(user = Depends(get_current_user)):
    return user

FastAPI has become my go-to for any Python backend work.

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