client = TestClient(app)


def test_security_http_bearer():
    response = client.get("/users/me", headers={"Authorization": "Bearer foobar"})
    assert response.status_code == 200, response.text
    assert response.json() == {"scheme": "Bearer", "credentials": "foobar"}


def test_security_http_bearer_no_credentials():
    response = client.get("/users/me")

    assert response.json() == {"detail": "Not authenticated"}
    assert response.headers["WWW-Authenticate"] == "Bearer"


@needs_py39
def test_token(client: TestClient):
    access_token = get_access_token(scope="me", client=client)
    response = client.get(
        "/users/me", headers={"Authorization": f"Bearer {access_token}"}
    )
    assert response.status_code == 200, response.text
    assert response.json() == {

from pydantic import BaseModel
from typing_extensions import Annotated

app = FastAPI()

bearer_scheme = HTTPBearer()


class Subscription(BaseModel):
    username: str
    monthly_fee: float
    start_date: datetime


@app.webhooks.post("new-subscription")
def new_subscription(
    body: Subscription, token: Annotated[str, Security(bearer_scheme)]
):
    """

    return current_user


client = TestClient(app)


def test_security_oauth2():
    response = client.get("/users/me", headers={"Authorization": "Bearer footokenbar"})
    assert response.status_code == 200, response.text
    assert response.json() == {"username": "Bearer footokenbar"}


def test_security_oauth2_password_other_header():
    response = client.get("/users/me", headers={"Authorization": "Other footokenbar"})

    return current_user


client = TestClient(app)


def test_security_oauth2():
    response = client.get("/users/me", headers={"Authorization": "Bearer footokenbar"})
    assert response.status_code == 200, response.text
    assert response.json() == {"username": "Bearer footokenbar"}


def test_security_oauth2_password_other_header():
    response = client.get("/users/me", headers={"Authorization": "Other footokenbar"})

            headers={"WWW-Authenticate": "Bearer"},
        )
    access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
    access_token = create_access_token(
        data={"sub": user.username}, expires_delta=access_token_expires
    )
    return Token(access_token=access_token, token_type="bearer")


@app.get("/users/me/", response_model=User)
async def read_users_me(

    * But it needs authentication for that specific endpoint.
    * So, to authenticate with our API, it sends a header `Authorization` with a value of `Bearer ` plus the token.
    * If the token contains `foobar`, the content of the `Authorization` header would be: `Bearer foobar`.

## **FastAPI**'s `OAuth2PasswordBearer`

**FastAPI** provides several tools, at different levels of abstraction, to implement these security features.

```Python hl_lines="58-67  69-72  90"
{!../../../docs_src/security/tutorial003.py!}
```

!!! info "说明"

    此处返回值为 `Bearer` 的响应头 `WWW-Authenticate` 也是规范的一部分。

    任何 401**UNAUTHORIZED**HTTP（错误）状态码都应返回 `WWW-Authenticate` 响应头。

    本例中，因为使用的是 Bearer Token，该响应头的值应为 `Bearer`。

    实际上，忽略这个附加响应头，也不会有什么问题。

    之所以在此提供这个附加响应头，是为了符合规范的要求。

    说不定什么时候，就有工具用得上它，而且，开发者或用户也可能用得上。

    这就是遵循标准的好处……

async def get_current_user(
    security_scopes: SecurityScopes, token: Annotated[str, Depends(oauth2_scheme)]
):
    if security_scopes.scopes:
        authenticate_value = f'Bearer scope="{security_scopes.scope_str}"'
    else:
        authenticate_value = "Bearer"
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",

    * したがって、APIで認証するため、HTTPヘッダー`Authorization`に`Bearer`の文字列とトークンを加えた値を送信します。
    * トークンに`foobar`が含まれている場合、`Authorization`ヘッダーの内容は次のようになります: `Bearer foobar`。

## **FastAPI**の`OAuth2PasswordBearer`

**FastAPI**は、これらのセキュリティ機能を実装するために、抽象度の異なる複数のツールを提供しています。

この例では、**Bearer**トークンを使用して**OAuth2**を**パスワード**フローで使用します。これには`OAuth2PasswordBearer`クラスを使用します。

!!! info "情報"
    「bearer」トークンが、唯一の選択肢ではありません。

    しかし、私たちのユースケースには最適です。