all !important;\n}\n\n.user-select-auto {\n  -webkit-user-select: auto !important;\n  -moz-user-select: auto !important;\n  user-select: auto !important;\n}\n\n.user-select-none {\n  -webkit-user-select: none !important;\n  -moz-user-select: none !important;\n  user-select: none !important;\n}\n\n.pe-none {\n  pointer-events: none !important;\n}\n\n.pe-auto {\n  pointer-events: auto !important;\n}\n\n.rounded {\n  border-radius: var(--bs-border-radius) !important;\n}\n\n.rounded-0 {\n  border-radius:...

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):

	ErrInvalidPart: {
		Code:           "InvalidPart",
		Description:    "One or more of the specified parts could not be found.  The part may not have been uploaded, or the specified entity tag may not match the part's entity tag.",
		HTTPStatusCode: http.StatusBadRequest,
	},
	ErrMissingPart: {
		Code:           "InvalidRequest",
		Description:    "You must specify at least one part",
		HTTPStatusCode: http.StatusBadRequest,
	},

ul.has-error {
	color: #dd4b39 !important;
	list-style-type: none;
	padding: 0;
}

.form-group .has-error + .form-control {
	border-color: #dd4b39 !important;
	box-shadow: none;
}

.sidebar-mini.sidebar-collapse .sidebar-search {
	display: none !important;
}

input[type="file"].form-control:not([type="file"]) {
	height: 0% !important;
}

#result ol {
	list-style: none !important;
	padding-left: 0;
}

</div>

Das bedeutet, dass es **immer einen Wert** hat, der Wert kann jedoch manchmal `None` sein (oder `null` in JSON).

Das bedeutet, dass Clients, die Ihre API verwenden, nicht prüfen müssen, ob der Wert vorhanden ist oder nicht. Sie können davon ausgehen, dass das Feld immer vorhanden ist. In einigen Fällen hat es jedoch nur den Defaultwert `None`.

)=>{this._isShown&&!this._isTransitioning&&this._adjustDialog()})),F.on(this._element,"mousedown.dismiss.bs.modal",(t=>{F.one(this._element,"click.dismiss.bs.modal",(e=>{this._element===t.target&&this._element===e.target&&("static"!==this._config.backdrop?this._config.backdrop&&this.hide():this._triggerBackdropTransition())}))}))}_hideModal(){this._element.style.display="none",this._element.setAttribute("aria-hidden",!0),this._element.removeAttribute("aria-modal"),this._element.removeAttribute("...

기본값 `None`을 `Query(None)`으로 바꿔야 하므로, `Query`의 첫 번째 매개변수는 기본값을 정의하는 것과 같은 목적으로 사용됩니다.

그러므로:

```Python
q: Optional[str] = Query(None)
```

...위 코드는 아래와 동일하게 매개변수를 선택적으로 만듭니다:

```Python
q: Optional[str] = None
```

하지만 명시적으로 쿼리 매개변수를 선언합니다.

/// info | 정보

FastAPI는 다음 부분에 관심이 있습니다:

```Python
= None
```

또는:

```Python
= Query(None)

}

#result .site cite {
	color: #093;
	font-style: normal;
}

#result .more {
	display: none;
}

#result .info {
	font-size: 80%;
}

#result .url-copy {
	color: #007bff;
}

#result .url-copied {
	color: #2c974b;
}

#result .favorited {
	display: none;
}

#result .favorited i {
	color: #fab005;
}

#result .thumbnail {
	width: 100px;

        elt = self.element.find('sts:{}'.format(name), _STS_NS)
        return STSElement(self.root_name, elt) if elt is not None else None

    def get_child_text(self, name, strict=True):
        """Extract text of a child element. If strict, and child element is
        not present, raises InvalidXMLError and otherwise returns
        None.

        """
        if strict:
            try:

Поскольку по умолчанию, отдельные значения интерпретируются как query-параметры, вам не нужно явно добавлять `Query`, вы можете просто сделать так:

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

Или в Python 3.10 и выше:

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

Например:

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

/// info | Информация