FastAPI has a powerful Dependency Injection system. Dependencies allow you to share logic, enforce security, manage database connections, and reduce code repetition.
app = FastAPI()
To keep a portable version of this guide on your local machine, print this webpage layout directly to a file or save it locally as a . This ensures you have access to syntax configurations, boilerplate setup, and data validation rules even while offline. If you would like to expand this guide, let me know: Should we add a section on JWT Authentication ? Share public link fastapi tutorial pdf
pip install fastapi
FastAPI automatically generates documentation for your endpoints based on your code structure and type hints. FastAPI has a powerful Dependency Injection system
Reuses standard logic, connection systems, or security rules raise HTTPException(404) Aborts operations to return strict semantic error codes How to Save This Tutorial as a PDF
FastAPI leverages Python type hints to validate incoming request data automatically. Path Parameters This ensures you have access to syntax configurations,
from datetime import datetime, timedelta from fastapi import Depends, FastAPI, HTTPException, status from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm from jose import JWTError, jwt from passlib.context import CryptContext # Configuration configurations SECRET_KEY = "SUPER_SECRET_SIGNING_KEY" ALGORITHM = "HS256" ACCESS_TOKEN_EXPIRE_MINUTES = 30 pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto") oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token") def verify_password(plain_password, hashed_password): return pwd_context.verify(plain_password, hashed_password) def get_password_hash(password): return pwd_context.hash(password) def create_access_token(data: dict): to_encode = data.copy() expire = datetime.utcnow() + timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES) to_encode.update("exp": expire) return jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM) app = FastAPI() @app.post("/token") async def login(form_data: OAuth2PasswordRequestForm = Depends()): # Example placeholder credential validation if form_data.username != "admin" or form_data.password != "secret": raise HTTPException(status_code=400, detail="Incorrect username or password") access_token = create_access_token(data="sub": form_data.username) return "access_token": access_token, "token_type": "bearer" @app.get("/secure-data") async def get_secure_data(token: str = Depends(oauth2_scheme)): try: payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM]) username: str = payload.get("sub") if username is None: raise HTTPException(status_code=401, detail="Invalid token") except JWTError: raise HTTPException(status_code=401, detail="Could not validate credentials") return "protected_info": f"Hello username, this data is protected by JWT tokens." Use code with caution. 9. Advanced Concepts Middlewares
# GET endpoint to retrieve all items @app.get("/items/") def read_items(): return items