FastAPI如何支持通过Authorization Header传递账号密码生成Token？

作为Python和FastAPI新手，使用官方OAuth2-JWT示例代码时，希望将登录接口从请求体传递用户名密码改为通过Authorization Header（Basic Auth）传递账号密码获取Token，但修改后遇到两个问题：

1. 直接调整依赖后报错，提示缺少请求体中的用户名和密码
2. 尝试将登录接口依赖替换为oauth2_scheme后，所有请求均返回未认证状态

要实现通过Basic Auth Header传递账号密码获取Token，需替换原有的OAuth2PasswordRequestForm依赖，改用HTTPBasic解析Header中的认证信息，具体步骤如下：

1. 新增HTTPBasic相关导入 #

从fastapi.security模块导入HTTPBasic和HTTPBasicCredentials，用于解析Header中的Basic Auth凭证。

2. 创建HTTPBasic实例 #

新增HTTPBasic实例，替代原有的表单依赖处理认证请求。

3. 修改登录接口逻辑 #

在登录接口中通过HTTPBasicCredentials获取用户名和密码，复用原有认证逻辑生成Token，并调整响应头提示客户端使用Basic Auth方式。

from datetime import datetime, timedelta
from typing import Union

from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, HTTPBasic, HTTPBasicCredentials  # 新增导入
from jose import JWTError, jwt
from passlib.context import CryptContext
from pydantic import BaseModel
from typing_extensions import Annotated

# 生成SECRET_KEY可执行命令：openssl rand -hex 32
SECRET_KEY = "09d25e094faa6ca2556c818166b7a9563b93f7099f6f0f4caa6cf63b88e8d3e7"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30


fake_users_db = {
    "johndoe": {
        "username": "johndoe",
        "full_name": "John Doe",
        "email": "johndoe@example.com",
        "hashed_password": "$2b$12$EixZaYVK1fsbw1ZfbX3OXePaWxn96p36WQoeG6Lruj3vjPGga31lW",
        "disabled": False,
    }
}


class Token(BaseModel):
    access_token: str
    token_type: str


class TokenData(BaseModel):
    username: Union[str, None] = None


class User(BaseModel):
    username: str
    email: Union[str, None] = None
    full_name: Union[str, None] = None
    disabled: Union[bool, None] = None


class UserInDB(User):
    hashed_password: str


pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")
basic_auth = HTTPBasic()  # 新增HTTPBasic实例

app = FastAPI()


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 get_user(db, username: str):
    if username in db:
        user_dict = db[username]
        return UserInDB(**user_dict)


def authenticate_user(fake_db, username: str, password: str):
    user = get_user(fake_db, username)
    if not user:
        return False
    if not verify_password(password, user.hashed_password):
        return False
    return user


def create_access_token(data: dict, expires_delta: Union[timedelta, None] = 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


async def get_current_user(token: Annotated[str, Depends(oauth2_scheme)]):
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        username: str = payload.get("sub")
        if username is None:
            raise credentials_exception
        token_data = TokenData(username=username)
    except JWTError:
        raise credentials_exception
    user = get_user(fake_users_db, username=token_data.username)
    if user is None:
        raise credentials_exception
    return user


async def get_current_active_user(
    current_user: Annotated[User, Depends(get_current_user)]
):
    if current_user.disabled:
        raise HTTPException(status_code=400, detail="Inactive user")
    return current_user


# 修改后的登录接口
@app.post("/token", response_model=Token)
async def login_for_access_token(
    credentials: Annotated[HTTPBasicCredentials, Depends(basic_auth)]
):
    user = authenticate_user(fake_users_db, credentials.username, credentials.password)
    if not user:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect username or password",
            headers={"WWW-Authenticate": "Basic"},  # 调整为Basic认证提示
        )
    access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
    access_token = create_access_token(
        data={"sub": user.username}, expires_delta=access_token_expires
    )
    return {"access_token": access_token, "token_type": "bearer"}


@app.get("/users/me/", response_model=User)
async def read_users_me(
    current_user: Annotated[User, Depends(get_current_active_user)]
):
    return current_user


@app.get("/users/me/items/")
async def read_own_items(
    current_user: Annotated[User, Depends(get_current_active_user)]
):
    return [{"item_id": "Foo", "owner": current_user.username}]

• 原代码的OAuth2PasswordRequestForm专门处理表单/请求体格式的用户名密码，而HTTPBasic负责解析Authorization: Basic <base64编码的用户名:密码>格式的请求头
• 登录接口的WWW-Authenticate响应头改为Basic，明确告知客户端需使用Basic Auth方式传递凭证
• 其他需要JWT认证的接口（如/users/me/）逻辑保持不变，依然通过oauth2_scheme验证Bearer Token

内容的提问来源于stack exchange，提问作者Chait Sang