## 응답 모델 인코딩 매개변수

응답 모델은 아래와 같이 기본값을 가질 수 있습니다:

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

* `description: Optional[str] = None`은 기본값으로 `None`을 갖습니다.
* `tax: float = 10.5`는 기본값으로 `10.5`를 갖습니다.
* `tags: List[str] = []` 빈 리스트의 기본값으로: `[]`.

그러나 실제로 저장되지 않았을 경우 결과에서 값을 생략하고 싶을 수 있습니다.

예를 들어, NoSQL 데이터베이스에 많은 선택적 속성이 있는 모델이 있지만, 기본값으로 가득 찬 매우 긴 JSON 응답을 보내고 싶지 않습니다.

app = FastAPI()


@app.get("/items/{item_id}")
async def read_items(
    *,
    item_id: int = Path(title="The ID of the item to get", ge=0, le=1000),
    q: str,
    size: float = Query(gt=0, lt=10.5),
):
    results = {"item_id": item_id}
    if q:
        results.update({"q": q})
    if size:
        results.update({"size": size})

    description: str | None = None
    price: float | None = None
    tax: float = 10.5
    tags: list[str] = []


items = {
    "foo": {"name": "Foo", "price": 50.2},
    "bar": {"name": "Bar", "description": "The bartenders", "price": 62, "tax": 20.2},
    "baz": {"name": "Baz", "description": None, "price": 50.2, "tax": 10.5, "tags": []},
}


@app.get("/items/{item_id}", response_model=Item)

app = FastAPI()


@app.get("/items/{item_id}")
async def read_items(
    *,
    item_id: Annotated[int, Path(title="The ID of the item to get", ge=0, le=1000)],
    q: str,
    size: Annotated[float, Query(gt=0, lt=10.5)],
):
    results = {"item_id": item_id}
    if q:
        results.update({"q": q})
    if size:
        results.update({"size": size})

    public static Properties copyProperties(Properties properties) {
        final Properties copyProperties = new Properties();
        // guard against modification/removal of keys in the given properties (MNG-5670, MNG-6053, MNG-6105)
        synchronized (properties) {
            copyProperties.putAll(properties);
        }
        return copyProperties;
    }

    "price": 3,
    "description": None,
}
```

weil das bereits gespeicherte Attribut `"tax": 20.2` nicht enthalten ist, das Eingabemodell den Defaultwert `"tax": 10.5` erhalten würde.

Und die Daten würden mit diesem „neuen“ `tax` von `10.5` gespeichert werden.

## Teil-Aktualisierungen mit `PATCH` { #partial-updates-with-patch }

        ),
        (
            "/items/baz",
            {
                "name": "Baz",
                "description": None,
                "price": 50.2,
                "tax": 10.5,
                "tags": [],
            },
        ),
    ],
)
def test_get(url, data, client: TestClient):
    response = client.get(url)
    assert response.status_code == 200, response.text

    "price": 3,
    "description": None,
}
```

debido a que no incluye el atributo ya almacenado `"tax": 20.2`, el modelo de entrada tomaría el valor por defecto de `"tax": 10.5`.

Y los datos se guardarían con ese "nuevo" `tax` de `10.5`.

## Actualizaciones parciales con `PATCH` { #partial-updates-with-patch }

{* ../../docs_src/response_model/tutorial004_py310.py hl[9,11:12] *}

* `description: Union[str, None] = None` (oder `str | None = None` in Python 3.10) hat einen Defaultwert `None`.
* `tax: float = 10.5` hat einen Defaultwert `10.5`.
* `tags: List[str] = []` hat eine leere Liste als Defaultwert: `[]`.

Aber Sie möchten diese vielleicht vom Resultat ausschließen, wenn Sie gar nicht gesetzt wurden.

{* ../../docs_src/response_model/tutorial004_py310.py hl[9,11:12] *}

* `description: Union[str, None] = None` (or `str | None = None` in Python 3.10) has a default of `None`.
* `tax: float = 10.5` has a default of `10.5`.
* `tags: List[str] = []` has a default of an empty list: `[]`.

but you might want to omit them from the result if they were not actually stored.