How can I implement authentication in FastAPI?

How can I implement authentication in FastAPI?

You can implement authentication in FastAPI using OAuth2 with Password Flow or JWT tokens. Would you like a code example?

Yes, please provide a code example for JWT authentication.

Sure! Here's a basic example:

from fastapi import FastAPI, Depends, HTTPException
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from jose import JWTError, jwt
from datetime import datetime, timedelta

app = FastAPI()

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")

# Your secret key and algorithm
SECRET_KEY = "your_secret_key"
ALGORITHM = "HS256"

# Function to create a JWT token
def create_access_token(data: dict, expires_delta: timedelta = None):
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=15)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt

# Example route to get a token
@app.post("/token")
async def login(form_data: OAuth2PasswordRequestForm = Depends()):
    # Validate user credentials here
    access_token = create_access_token(data={"sub": form_data.username})
    return {"access_token": access_token, "token_type": "bearer"}

This is a simple implementation. Would you like to know more about securing your endpoints?

Yes, how do I secure my endpoints using the token?

You can secure your endpoints by using the Depends function with the oauth2_scheme. Here's an example:

from fastapi import Security

@app.get("/users/me")
async def read_users_me(token: str = Depends(oauth2_scheme)):
    # Validate the token and get user info
    return {"token": token}

This will require a valid token to access the /users/me endpoint.