👯‍♂️ 💼 👉 ⛓ 👈 `item` 💪 `int` ⚖️ `str`.

#### 🎲 `None`

👆 💪 📣 👈 💲 💪 ✔️ 🆎, 💖 `str`, ✋️ 👈 ⚫️ 💪 `None`.

🐍 3️⃣.6️⃣ & 🔛 (✅ 🐍 3️⃣.1️⃣0️⃣) 👆 💪 📣 ⚫️ 🏭 & ⚙️ `Optional` ⚪️➡️ `typing` 🕹.

```Python hl_lines="1  4"
{!../../docs_src/python_types/tutorial009.py!}
```

⚙️ `Optional[str]` ↩️ `str` 🔜 ➡️ 👨‍🎨 ℹ 👆 🔍 ❌ 🌐❔ 👆 💪 🤔 👈 💲 🕧 `str`, 🕐❔ ⚫️ 💪 🤙 `None` 💁‍♂️.

    }

    @Override
    public void tearDown() throws Exception {
        currentSsoType = Constants.NONE;
        super.tearDown();
    }

    // Test available() method
    public void test_available_withNoneSsoType() {
        currentSsoType = Constants.NONE;
        assertFalse(ssoManager.available());
    }

    public void test_available_withValidSsoType() {

```Python
q: Union[str, None] = None
```

Ou bien, en Python 3.10 et supérieur :

```Python
q: str | None = None
```

Par exemple :

{* ../../docs_src/body_multiple_params/tutorial004_an_py310.py hl[27] *}

/// info

/// note

FastAPI will know that the value of `q` is not required because of the default value `= None`.

The `str | None` (Python 3.10+) or `Union` in `Union[str, None]` (Python 3.8+) is not used by FastAPI to determine that the value is not required, it will know it's not required because it has a default value of `= None`.

But adding the type annotations will allow your editor to give you better support and detect errors.

///

👉 💼, 👆 💪 ❎ 📨 🏷 ⚡ ⚒ `response_model=None`:

{* ../../docs_src/response_model/tutorial003_05.py hl[9] *}

👉 🔜 ⚒ FastAPI 🚶 📨 🏷 ⚡ & 👈 🌌 👆 💪 ✔️ 🙆 📨 🆎 ✍ 👆 💪 🍵 ⚫️ 🤕 👆 FastAPI 🈸. 👶

## 📨 🏷 🔢 🔢

👆 📨 🏷 💪 ✔️ 🔢 💲, 💖:

{* ../../docs_src/response_model/tutorial004.py hl[11,13:14] *}

* `description: Union[str, None] = None` (⚖️ `str | None = None` 🐍 3️⃣.1️⃣0️⃣) ✔️ 🔢 `None`.

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}")
def update_item(item_id: int, item: Item):

`Optional[Something]` é na verdade um atalho para `Union[Something, None]`, eles são equivalentes.

Isso também significa que no Python 3.10, você pode utilizar `Something | None`:

//// tab | Python 3.10+

```Python hl_lines="1"
{!> ../../docs_src/python_types/tutorial009_py310.py!}
```

    font-size: 10pt;
    color: #000000;
    text-decoration: none
}
a.plain {
    display: inline;
    float: none;
    width: auto;
    height: auto
}
a.sort {
    display: block;
    float: left;
    width: 100px;
    height: 15px;
    font-family: Verdana, sans-serif;
    font-size: 8pt;
    font-weight: bold;
    text-decoration: none;
    color: #000000;
    background-color: #d0d0d0;

## 선택적 매개변수

같은 방법으로 기본값을 `None`으로 설정하여 선택적 매개변수를 선언할 수 있습니다:

{* ../../docs_src/query_params/tutorial002.py hl[9] *}

이 경우 함수 매개변수 `q`는 선택적이며 기본값으로 `None` 값이 됩니다.

/// check | 확인

**FastAPI**는 `item_id`가 경로 매개변수이고 `q`는 경로 매개변수가 아닌 쿼리 매개변수라는 것을 알 정도로 충분히 똑똑합니다.

///

/// note | 참고

FastAPI는 `q`가 `= None`이므로 선택적이라는 것을 인지합니다.

    * Вы можете задать его URL с помощью параметра `docs_url`.
    * Вы можете отключить это с помощью настройки `docs_url=None`.
* **ReDoc**: отображаемый по адресу `/redoc`.
    * Вы можете задать его URL с помощью параметра `redoc_url`.
    * Вы можете отключить это с помощью настройки `redoc_url=None`.

К примеру, чтобы задать отображение Swagger UI по адресу `/documentation` и отключить ReDoc: