After module 8: Authentication

carsharing.py

@@ -1,18 +1,22 @@
 import uvicorn
-from fastapi import FastAPI, Request
+from fastapi import FastAPI
+from fastapi import Request
 from fastapi.middleware.cors import CORSMiddleware
-from sqlmodel import SQLModel
+from fastapi.security import HTTPBasic, HTTPBasicCredentials
+from sqlmodel import SQLModel, Session, select
+from starlette import status
 from starlette.responses import JSONResponse
 from starlette.status import HTTP_422_UNPROCESSABLE_ENTITY
 
-from db import engine
-from routers import cars, web
+from db import engine, get_session
+from routers import cars, web, auth
 from routers.cars import BadTripException
+from schemas import UserOutput, User
 
 app = FastAPI(title="Car Sharing")
 app.include_router(web.router)
 app.include_router(cars.router)
-
+app.include_router(auth.router)
 
 origins = [
     "http://localhost:8000",
@@ -50,4 +54,3 @@ async def add_cars_cookie(request: Request, call_next):
 
 if __name__ == "__main__":
     uvicorn.run("carsharing:app", reload=True)
-

create_user.py

@@ -0,0 +1,36 @@
+"""
+create_user.py
+-------------
+A convenience script to create a user.
+"""
+
+from getpass import getpass
+
+from sqlmodel import SQLModel, Session, create_engine
+
+from schemas import User
+
+
+engine = create_engine(
+    "sqlite:///carsharing.db",
+    connect_args={"check_same_thread": False},  # Needed for SQLite
+    echo=True # Log generated SQL
+)
+
+
+if __name__ == "__main__":
+    print("Creating tables (if necessary)")
+    SQLModel.metadata.create_all(engine)
+
+    print("--------")
+
+    print("This script will create a user and save it in the database.")
+
+    username = input("Please enter username\n")
+    pwd = getpass("Please enter password\n")
+
+    with Session(engine) as session:
+        user = User(username=username)
+        user.set_password(pwd)
+        session.add(user)
+        session.commit()

routers/auth.py

@@ -0,0 +1,36 @@
+from fastapi import Depends, HTTPException, APIRouter
+from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
+from sqlmodel import Session, select
+from starlette import status
+
+from db import get_session
+from schemas import UserOutput, User
+
+URL_PREFIX="/auth"
+router = APIRouter(prefix=URL_PREFIX)
+oauth2_scheme = OAuth2PasswordBearer(tokenUrl=f"{URL_PREFIX}/token")
+
+
+def get_current_user(token: str = Depends(oauth2_scheme),
+                 session: Session = Depends(get_session)) -> UserOutput:
+    query = select(User).where(User.username == token)
+    user = session.exec(query).first()
+    if user:
+        return UserOutput.from_orm(user)
+    else:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Username or password incorrect",
+            headers={"WWW-Authenticate": "Bearer"},
+        )
+
+
+@router.post("/token")
+async def login(form_data: OAuth2PasswordRequestForm = Depends(),
+                session: Session = Depends(get_session)):
+    query = select(User).where(User.username == form_data.username)
+    user = session.exec(query).first()
+    if user and user.verify_password(form_data.password):
+        return {"access_token": user.username, "token_type": "bearer"}
+    else:
+        raise HTTPException(status_code=400, detail="Incorrect username or password")

routers/cars.py

@@ -1,9 +1,9 @@
 from fastapi import Depends, HTTPException, APIRouter
 from sqlmodel import Session, select
 
+from routers.auth import get_current_user
 from db import get_session
-from schemas import Car, CarOutput, CarInput, Trip, TripInput
-
+from schemas import Car, CarOutput, CarInput, Trip, TripInput, User
 
 router = APIRouter(prefix="/api/cars")
 
@@ -29,7 +29,9 @@ def car_by_id(id: int, session: Session = Depends(get_session)) -> Car:
 
 
 @router.post("/", response_model=Car)
-def add_car(car_input: CarInput, session: Session = Depends(get_session)) -> Car:
+def add_car(car_input: CarInput,
+            session: Session = Depends(get_session),
+            user: User = Depends(get_current_user)) -> Car:
     new_car = Car.from_orm(car_input)
     session.add(new_car)
     session.commit()

schemas.py

@@ -1,4 +1,25 @@
-from sqlmodel import SQLModel, Field, Relationship
+from sqlmodel import SQLModel, Field, Relationship, Column, VARCHAR
+from passlib.context import CryptContext
+
+pwd_context = CryptContext(schemes=["bcrypt"])
+
+class UserOutput(SQLModel):
+    id: int
+    username: str
+
+
+class User(SQLModel, table=True):
+    id: int | None = Field(default=None, primary_key=True)
+    username: str = Field(sa_column=Column("username", VARCHAR, unique=True, index=True))
+    password_hash: str = ""
+
+    def set_password(self, password):
+        """Setting the passwords actually sets password_hash."""
+        self.password_hash = pwd_context.hash(password)
+
+    def verify_password(self, password):
+        """Verify given password by hashing and comparing to password_hash."""
+        return pwd_context.verify(password, self.password_hash)
 
 
 class TripInput(SQLModel):