Quickly Authenticate Users with FastAPI and Token Authentication

Authentication is a crucial aspect of web application development. FastAPI, a modern web framework for building APIs with Python, provides an efficient way to authenticate users using token authentication. Token authentication involves the use of a token, usually a long string of characters, to verify the identity of a user.

Here’s how you can quickly authenticate users with FastAPI and token authentication:

Step 1: Install FastAPI

First, you need to install FastAPI. You can do this by using pip, the package installer for Python:


pip install fastapi


Step 2: Create a User Model

Next, create a user model that will store the user’s data, including their username and password. This model will be used for authentication:


from pydantic import BaseModel

class User(BaseModel):
username: str
password: str


Step 3: Generate a Token for Authentication

Using FastAPI, you can generate a token for authentication by using the JWT (JSON Web Tokens) library. This token will be used to verify the identity of the user:


import jwt
from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm

@app.post("/token")
async def login(form_data: OAuth2PasswordRequestForm = Depends()):
# Use the username and password to authenticate the user
user = authenticate_user(fake_users_db, form_data.username, form_data.password)
if not user:
raise HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail="Incorrect username or password",
headers={"WWW-Authenticate": "Bearer"},
)
# Generate and return the token
token = create_access_token(data={"sub": user.username})
return {"access_token": token, "token_type": "bearer"}


Step 4: Protect API Endpoints with Authentication

Finally, you can protect your API endpoints by using the generated token for authentication. This will ensure that only authenticated users have access to specific resources:


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

@app.get("/users/me")
async def read_users_me(current_user: User = Depends(get_current_user)):
return current_user


By following these steps, you can quickly authenticate users with FastAPI and token authentication, ensuring that your web application is secure and only accessible to authorized users.