FastAPI-Users中AuthenticationBackend报AttributeError: transport错误求助

问题重现 #

使用FastAPI-Users实现授权认证功能时，将JWT作为AuthenticationBackend的transport属性配置，但持续触发AttributeError: transport错误。已尝试重写代码、更新并重新安装库，且确认库源码中AuthenticationBackend类确实存在transport属性，代码参考官方文档实现。

报错栈 #

File "C:\Users\User\AppData\Local\Programs\Python\Python311\Lib\multiprocessing\process.py", line 314, in _bootstrap
    self.run()
  File "C:\Users\User\AppData\Local\Programs\Python\Python311\Lib\multiprocessing\process.py", line 108, in run
    self._target(*self._args, **self._kwargs)
  File "C:\Users\User\AppData\Local\Programs\Python\Python311\Lib\site-packages\uvicorn\_subprocess.py", line 76, in subprocess_started
    target(sockets=sockets)
  File "C:\Users\User\AppData\Local\Programs\Python\Python311\Lib\site-packages\uvicorn\server.py", line 61, in run
    return asyncio.run(self.serve(sockets=sockets))
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\User\AppData\Local\Programs\Python\Python311\Lib\asyncio\runners.py", line 190, in run
    return runner.run(main)
           ^^^^^^^^^^^^^^^^
  File "C:\Users\User\AppData\Local\Programs\Python\Python311\Lib\asyncio\runners.py", line 118, in run
    return self._loop.run_until_complete(task)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\User\AppData\Local\Programs\Python\Python311\Lib\asyncio\base_events.py", line 653, in run_until_complete
    return future.result()
           ^^^^^^^^^^^^^^^
  File "C:\Users\User\AppData\Local\Programs\Python\Python311\Lib\site-packages\uvicorn\server.py", line 68, in serve
    config.load()
  File "C:\Users\User\AppData\Local\Programs\Python\Python311\Lib\site-packages\uvicorn\config.py", line 467, in load
    self.loaded_app = import_from_string(self.app)
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\User\AppData\Local\Programs\Python\Python311\Lib\site-packages\uvicorn\importer.py", line 21, in import_from_string
    module = importlib.import_module(module_str)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\User\AppData\Local\Programs\Python\Python311\Lib\importlib\__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen importlib._bootstrap>", line 1206, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1178, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1149, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 690, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 940, in exec_module
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "D:\Pyton\MyProject\fastapi_shop\main.py", line 24, in <module>
    fastapi_users.get_auth_router(UserRead, UserCreate),
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\User\AppData\Local\Programs\Python\Python311\Lib\site-packages\fastapi_users\fastapi_users.py", line 84, in get_auth_router
    return get_auth_router(
           ^^^^^^^^^^^^^^^^
  File "C:\Users\User\AppData\Local\Programs\Python\Python311\Lib\site-packages\fastapi_users\router\auth.py", line 43, in get_auth_router
    **backend.transport.get_openapi_login_responses_success(),
      ^^^^^^^^^^^^^^^^^
  File "C:\Users\User\AppData\Local\Programs\Python\Python311\Lib\site-packages\pydantic\_internal\_model_construction.py", line 210, in __getattr__
    raise AttributeError(item)
AttributeError: transport

相关代码 #

AuthenticationBackend配置 #

auth_backend = AuthenticationBackend(
    name="jwt",
    transport=bearer_transport,
    get_strategy=get_jwt_strategy,
)

导入语句 #

from fastapi_users.authentication import (
    AuthenticationBackend,
    BearerTransport,
    JWTStrategy,
)

解决方案 #

• 版本兼容性检查：确认FastAPI-Users版本与参考的10.1版本文档匹配。执行pip show fastapi-users查看版本，若版本不符，安装指定版本：

  pip install fastapi-users==10.1.0
  

• 验证bearer_transport实例化：确保bearer_transport是BearerTransport的有效实例，正确写法示例：

  bearer_transport = BearerTransport(tokenUrl="auth/jwt/login")
  

• 检查FastAPIUsers实例初始化：确认创建FastAPIUsers对象时正确传入auth_backend参数，示例：

  fastapi_users = FastAPIUsers[UserDB, uuid.UUID](
      get_user_manager,
      [auth_backend],
  )
  

• 清理缓存重装库：彻底卸载后清理缓存再重装，避免旧版本残留：

  pip uninstall -y fastapi-users
  pip cache purge
  pip install fastapi-users==10.1.0
  

内容的提问来源于stack exchange，提问作者Castro_mx