FastAPI Guide for Building APIs

Table of Contents

1. FastAPI Basics

from fastapi import FastAPI

app = FastAPI()

@app.get("/")
def read_root():
    return {"Hello": "World"}

2. Endpoints

@app.get("/items/{item_id}")
def read_item(item_id: int, q: str = None):
    return {"item_id": item_id, "q": q}

@app.post("/items/")
def create_item(item: Item):
    return item

3. Request/Response

from pydantic import BaseModel

class Item(BaseModel):
    name: str
    description: str = None
    price: float
    tax: float = None

4. Authentication

from fastapi import Depends, HTTPException
from fastapi.security import OAuth2PasswordBearer

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")

@app.get("/users/me")
def read_users_me(token: str = Depends(oauth2_scheme)):
    return {"token": token}

5. Deployment

# Run with uvicorn
uvicorn main:app --reload

# Deploy to Render
# 1. Create Dockerfile
# 2. Push to GitHub
# 3. Connect to Render
# 4. Deploy

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