with patch.object(fastapi.cli, "cli_main", None):
        with pytest.raises(RuntimeError) as exc_info:
            fastapi.cli.main()

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/")

**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"

from typing_extensions import Annotated

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/")

from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    price: float
    is_offer: Union[bool, None] = None


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}


@app.put("/items/{item_id}")

# Get Current User

In the previous chapter the security system (which is based on the dependency injection system) was giving the *path operation function* a `token` as a `str`:

//// 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!}
```

////

from fastapi import FastAPI, Form
from fastapi.testclient import TestClient
from typing_extensions import Annotated

app = FastAPI()


@app.post("/form/")
def post_form(username: Annotated[str, Form()]):
    return username


client = TestClient(app)


def test_single_form_field():
    response = client.post("/form/", data={"username": "Rick"})
    assert response.status_code == 200, response.text

oauth2_scheme = OAuth2PasswordBearer(
    tokenUrl="/token",
    description="OAuth2PasswordBearer security scheme",
    auto_error=False,
)


@app.get("/items/")
async def read_items(token: Optional[str] = Security(oauth2_scheme)):
    if token is None:
        return {"msg": "Create an account first"}
    return {"token": token}


client = TestClient(app)


def test_no_token():

from .utils import needs_py310


def get_client():
    app = FastAPI()
    with pytest.warns(DeprecationWarning):

        @app.post("/items/")
        async def read_items(
            q: Annotated[str | None, Form(regex="^fixedquery$")] = None,
        ):
            if q:
                return f"Hello {q}"
            else:
                return "Hello World"

    client = TestClient(app)
    return client

media_type = "application/vnd.api+json"


# NOTE: These are not valid JSON:API resources
# but they are fine for testing requestBody with custom media_type
class Product(BaseModel):
    name: str
    price: float


class Shop(BaseModel):
    name: str


@app.post("/products")
async def create_product(data: Product = Body(media_type=media_type, embed=True)):
    pass  # pragma: no cover


@app.post("/shops")