informa ao SQLModel que o `id` é a **chave primária** no banco de dados SQL (você pode aprender mais sobre chaves primárias SQL na documentação do SQLModel).

    **Nota:** Usamos `int | None` para o campo de chave primária para que, no código Python, possamos *criar um objeto sem um `id`* (`id=None`), assumindo que o banco de dados irá *gerá-lo ao salvar*. O SQLModel entende que o banco de dados fornecerá o `id` e *define a coluna como um `INTEGER` não nulo* no esquema do banco de dados. Veja...

        isFocusList = false;
      } else if (e.keyCode === KEY_CODES.UP) {
        if ($boxElement.css("display") !== "none") {
          e.preventDefault();
        }
        suggestor.selectlist("up");
      } else if (e.keyCode === KEY_CODES.DOWN) {
        if ($boxElement.css("display") === "none") {
          suggestor.suggest();
        } else {
          suggestor.selectlist("down");
        }

/// note | Hinweis

FastAPI weiß, dass der Wert von `q` nicht erforderlich ist, aufgrund des definierten Defaultwertes `= None`.

Das `str | None` wird von FastAPI nicht verwendet, um zu bestimmen, dass der Wert nicht erforderlich ist. FastAPI weiß, dass er nicht erforderlich ist, weil er einen Defaultwert von `= None` hat.

Und Sie können auch Body-Parameter als optional kennzeichnen, indem Sie den Defaultwert auf `None` setzen:

{* ../../docs_src/body_multiple_params/tutorial001_an_py310.py hl[18:20] *}

/// note | Hinweis

Beachten Sie, dass in diesem Fall das `item`, welches vom Body genommen wird, optional ist. Da es `None` als Defaultwert hat.

///

## Mehrere Body-Parameter { #multiple-body-parameters }

And you can also declare body parameters as optional, by setting the default to `None`:

{* ../../docs_src/body_multiple_params/tutorial001_an_py310.py hl[18:20] *}

/// note

Notice that, in this case, the `item` that would be taken from the body is optional. As it has a `None` default value.

///

## Multiple body parameters { #multiple-body-parameters }

from typing import Annotated

from fastapi import FastAPI
from fastapi.temp_pydantic_v1_params import Body
from pydantic.v1 import BaseModel


class Item(BaseModel):
    name: str
    description: str | None = None
    size: float


app = FastAPI()


@app.post("/items/")
async def create_item(item: Annotated[Item, Body(embed=True)]) -> Item:

from fastapi import FastAPI

app = FastAPI()


@app.get("/items/{item_id}")
async def read_item(item_id: str, q: str | None = None, short: bool = False):
    item = {"item_id": item_id}
    if q:
        item.update({"q": q})
    if not short:
        item.update(
            {"description": "This is an amazing item that has a long description"}
        )

				t.Errorf("#%d: %q: expected error %q; got none", i, test.input, test.error)
			}
			continue
		}
		if !strings.Contains(err.Error(), test.error) {
			t.Errorf("#%d: expected error %q; got %q", i, test.error, err)
			continue
		}
	}
}

func runBadTest(i int, test badExprTest, t *testing.T) (err error) {
	p := NewParser(nil, nil, nil) // Expression evaluation uses none of these fields of the parser.

from fastapi import FastAPI, Path, Query

app = FastAPI()


@app.get("/items/{item_id}")
async def read_items(
    item_id: Annotated[int, Path(title="The ID of the item to get")],
    q: Annotated[str | None, Query(alias="item-query")] = None,
):
    results = {"item_id": item_id}
    if q:
        results.update({"q": q})

from functools import partial

from fastapi import FastAPI
from fastapi.testclient import TestClient


def main(some_arg, q: str | None = None):
    return {"some_arg": some_arg, "q": q}


endpoint = partial(main, "foo")

app = FastAPI()

app.get("/")(endpoint)


client = TestClient(app)


def test_partial():
    response = client.get("/?q=bar")
    data = response.json()