from typing import Annotated

from fastapi import Depends, FastAPI

app = FastAPI()


class FixedContentQueryChecker:
    def __init__(self, fixed_content: str):
        self.fixed_content = fixed_content

    def __call__(self, q: str = ""):
        if q:
            return self.fixed_content in q
        return False


checker = FixedContentQueryChecker("bar")


@app.get("/query-checker/")

from functools import lru_cache

from fastapi import Depends, FastAPI

from .config import Settings

app = FastAPI()


@lru_cache
def get_settings():
    return Settings()


@app.get("/info")
async def info(settings: Settings = Depends(get_settings)):
    return {
        "app_name": settings.app_name,
        "admin_email": settings.admin_email,
        "items_per_user": settings.items_per_user,

from contextvars import ContextVar
from typing import Any, Awaitable, Callable, Dict, Optional

from fastapi import Depends, FastAPI, Request, Response
from fastapi.testclient import TestClient

legacy_request_state_context_var: ContextVar[Optional[Dict[str, Any]]] = ContextVar(
    "legacy_request_state_context_var", default=None
)

app = FastAPI()


async def set_up_request_state_dependency():
    request_state = {"user": "deadpond"}

from fastapi import Depends, FastAPI, Security
from fastapi.security import APIKeyCookie
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()

api_key = APIKeyCookie(name="key")


class User(BaseModel):
    username: str


def get_current_user(oauth_header: str = Security(api_key)):
    user = User(username=oauth_header)
    return user


@app.get("/users/me")

from fastapi import Depends, FastAPI, Security
from fastapi.security import APIKeyCookie
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()

api_key = APIKeyCookie(name="key", description="An API Cookie Key")


class User(BaseModel):
    username: str


def get_current_user(oauth_header: str = Security(api_key)):
    user = User(username=oauth_header)
    return user

from functools import lru_cache
from typing import Annotated

from fastapi import Depends, FastAPI

from .config import Settings

app = FastAPI()


@lru_cache
def get_settings():
    return Settings()


@app.get("/info")
async def info(settings: Annotated[Settings, Depends(get_settings)]):
    return {
        "app_name": settings.app_name,
        "admin_email": settings.admin_email,

from fastapi import Depends, FastAPI

app = FastAPI()


fake_items_db = [{"item_name": "Foo"}, {"item_name": "Bar"}, {"item_name": "Baz"}]


class CommonQueryParams:
    def __init__(self, q: Union[str, None] = None, skip: int = 0, limit: int = 100):
        self.q = q
        self.skip = skip
        self.limit = limit


@app.get("/items/")
async def read_items(commons: CommonQueryParams = Depends()):
    response = {}

from fastapi import Depends, FastAPI, HTTPException

app = FastAPI()


class InternalError(Exception):
    pass


def get_username():
    try:
        yield "Rick"
    except InternalError:
        print("Oops, we didn't raise again, Britney 😱")


@app.get("/items/{item_id}")
def get_item(item_id: str, username: str = Depends(get_username)):
    if item_id == "portal-gun":
        raise InternalError(

from fastapi import Depends, FastAPI

app = FastAPI()


class FixedContentQueryChecker:
    def __init__(self, fixed_content: str):
        self.fixed_content = fixed_content

    def __call__(self, q: str = ""):
        if q:
            return self.fixed_content in q
        return False


checker = FixedContentQueryChecker("bar")


@app.get("/query-checker/")

```Python hl_lines="4  139  166"
{!../../docs_src/security/tutorial005.py!}
```

/// info | "技术细节"

`Security` 实际上是 `Depends` 的子类，而且只比 `Depends` 多一个参数。

但使用 `Security` 代替 `Depends`，**FastAPI** 可以声明安全作用域，并在内部使用这些作用域，同时，使用 OpenAPI 存档 API。

但实际上，从 `fastapi` 导入的 `Query`、`Path`、`Depends`、`Security` 等对象，只是返回特殊类的函数。

///

## 使用 `SecurityScopes`

修改依赖项 `get_current_user`。

这是上面的依赖项使用的依赖项。