from typing import Optional

from fastapi import FastAPI, Security
from fastapi.security import OAuth2AuthorizationCodeBearer
from fastapi.testclient import TestClient

app = FastAPI()

oauth2_scheme = OAuth2AuthorizationCodeBearer(
    authorizationUrl="authorize", tokenUrl="token", auto_error=True
)


@app.get("/items/")
async def read_items(token: Optional[str] = Security(oauth2_scheme)):
    return {"token": token}

from typing import Optional

from fastapi import FastAPI, Security
from fastapi.security import OAuth2AuthorizationCodeBearer
from fastapi.testclient import TestClient

app = FastAPI()

oauth2_scheme = OAuth2AuthorizationCodeBearer(
    authorizationUrl="authorize",
    tokenUrl="token",
    description="OAuth2 Code Bearer",
    auto_error=True,
)


@app.get("/items/")

from .http import HTTPBasicCredentials as HTTPBasicCredentials
from .http import HTTPBearer as HTTPBearer
from .http import HTTPDigest as HTTPDigest
from .oauth2 import OAuth2 as OAuth2
from .oauth2 import OAuth2AuthorizationCodeBearer as OAuth2AuthorizationCodeBearer
from .oauth2 import OAuth2PasswordBearer as OAuth2PasswordBearer
from .oauth2 import OAuth2PasswordRequestForm as OAuth2PasswordRequestForm

    APIKeyCookie,
    APIKeyHeader,
    APIKeyQuery,
    HTTPAuthorizationCredentials,
    HTTPBasic,
    HTTPBasicCredentials,
    HTTPBearer,
    HTTPDigest,
    OAuth2,
    OAuth2AuthorizationCodeBearer,
    OAuth2PasswordBearer,
    OAuth2PasswordRequestForm,
    OAuth2PasswordRequestFormStrict,
    OpenIdConnect,
    SecurityScopes,
)
```

## API Key Security Schemes

                    headers={"WWW-Authenticate": "Bearer"},
                )
            else:
                return None
        return param


class OAuth2AuthorizationCodeBearer(OAuth2):
    """
    OAuth2 flow for authentication using a bearer token obtained with an OAuth2 code
    flow. An instance of it would be used as a dependency.
    """

    def __init__(

* Add link to Chinese article in [External Links](https://fastapi.tiangolo.com/external-links/). PR [810](https://github.com/tiangolo/fastapi/pull/810) by [@wxq0309](https://github.com/wxq0309).
* Implement `OAuth2AuthorizationCodeBearer` class. PR [#797](https://github.com/tiangolo/fastapi/pull/797) by [@kuwv](https://github.com/kuwv).