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: 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 = {}

    return html


@pytest.fixture(name="client")
def get_client(app: FastAPI):
    client = TestClient(app)

    return client


@needs_py39
def test_get(client: TestClient, html: str):
    response = client.get("/")
    assert response.text == html


@needs_py39
def test_websocket_handle_disconnection(client: TestClient):

**FastAPI** はそれらを解決してくれます。

### 最初の依存関係「依存可能なもの」

以下のような最初の依存関係（「依存可能なもの」）を作成することができます:

```Python hl_lines="8 9"
{!../../docs_src/dependencies/tutorial005.py!}
```

これはオプショナルのクエリパラメータ`q`を`str`として宣言し、それを返すだけです。

これは非常にシンプルです（あまり便利ではありません）が、サブ依存関係がどのように機能するかに焦点を当てるのに役立ちます。

### 第二の依存関係 「依存可能なもの」と「依存」

そして、別の依存関数（「依存可能なもの」）を作成して、同時にそれ自身の依存関係を宣言することができます（つまりそれ自身も「依存」です）:

```Python hl_lines="13"

        }
    }


    public static int enc_utf8 ( String str, byte[] dst, int di, int dlim ) {
        int start = di, ch;
        int strlen = str.length();

        for ( int i = 0; di < dlim && i < strlen; i++ ) {
            ch = str.charAt(i);
            if ( ( ch >= 0x0001 ) && ( ch <= 0x007F ) ) {
                dst[ di++ ] = (byte) ch;
            }

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=Depends(CommonQueryParams)):

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: 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: Annotated[CommonQueryParams, Depends()]):

from typing import Union

from fastapi import FastAPI, Query
from typing_extensions import Annotated

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: Annotated[
        Union[str, None],
        Query(
            alias="item-query",
            title="Query string",
            description="Query string for the items to search in the database that have a good match",
            min_length=3,

# Aktuellen Benutzer abrufen

Im vorherigen Kapitel hat das Sicherheitssystem (das auf dem Dependency Injection System basiert) der *Pfadoperation-Funktion* einen `token` vom Typ `str` überreicht:

//// tab | Python 3.9+

```Python hl_lines="12"
{!> ../../docs_src/security/tutorial001_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="11"
{!> ../../docs_src/security/tutorial001_an.py!}
```

////

//// tab | 파이썬 3.7 이상

```Python hl_lines="25"
{!> ../../docs_src/security/tutorial002.py!}
```

////

//// tab | 파이썬 3.10 이상

```Python hl_lines="23"
{!> ../../docs_src/security/tutorial002_py310.py!}
```

////

## 유저 가져오기

`get_current_user`는 토큰을 `str`로 취하고 Pydantic `User` 모델을 반환하는 우리가 만든 (가짜) 유틸리티 함수를 사용합니다.

            "scopes": {"read:users": "Read the users", "write:users": "Create users"},
        }
    }
)


class User(BaseModel):
    username: str


# Here we use string annotations to test them
def get_current_user(oauth_header: "str" = Security(reusable_oauth2)):
    user = User(username=oauth_header)
    return user


@app.post("/login")
# Here we use string annotations to test them