```Python hl_lines="7-11"
{!../../docs_src/body/tutorial001.py!}
```

Также как и при описании параметров запроса, когда атрибут модели имеет значение по умолчанию, он является необязательным. Иначе он обязателен. Используйте `None`, чтобы сделать его необязательным без использования конкретных значений по умолчанию.

Например, модель выше описывает вот такой JSON "объект" (или словарь Python):

```JSON
{
    "name": "Foo",

        {
            "detail": [
                {
                    "type": "missing",
                    "loc": ["body", "files"],
                    "msg": "Field required",
                    "input": None,
                }
            ]
        }
    ) | IsDict(
        # TODO: remove when deprecating Pydantic v1
        {
            "detail": [
                {
                    "loc": ["body", "files"],

			return err
		}
	}
	fmt.Fprintln(c.Stdout, string(out))
	return nil
}

func waypointName(wl *ZtunnelWorkload, services []*ZtunnelService) string {
	if wl.Waypoint == nil {
		return "None"
	}

	for _, svc := range services {
		if fmt.Sprintf("%s/%s", svc.Namespace, svc.Hostname) == wl.Waypoint.Destination {
			return svc.Name
		}
		for _, addr := range svc.Addresses {

/**
 * @author higa
 */
public class BeanMapTest {

    /**
     * @see org.junit.rules.ExpectedException
     */
    @Rule
    public ExpectedException exception = ExpectedException.none();

    /**
     * @throws Exception
     */
    @Test
    public void testGet() throws Exception {
        final BeanMap map = new BeanMap();
        map.put("aaa", 1);
        map.put("bbb", 2);

                DependencyScope.TEST.isTransitive(),
                byProjectPath(CommonBuilds.PROJECT_PATH_TEST)));
        result.add(internalScopeManager.createDependencyScope(
                DependencyScope.NONE.id(), DependencyScope.NONE.isTransitive(), Collections.emptySet()));
        result.add(internalScopeManager.createDependencyScope(
                DependencyScope.COMPILE_ONLY.id(),
                DependencyScope.COMPILE_ONLY.isTransitive(),

from fastapi import FastAPI
from fastapi.testclient import TestClient

app = FastAPI(swagger_ui_oauth2_redirect_url=None)


@app.get("/items/")
async def read_items():
    return {"id": "foo"}


client = TestClient(app)


def test_swagger_ui():
    response = client.get("/docs")
    assert response.status_code == 200, response.text
    assert response.headers["content-type"] == "text/html; charset=utf-8"

app = FastAPI()


class ModelB(BaseModel):
    username: str


class ModelC(ModelB):
    password: str


class ModelA(BaseModel):
    name: str
    description: Optional[str] = None
    model_b: ModelB

    @validator("name")
    def lower_username(cls, name: str, values):
        if not name.endswith("A"):
            raise ValueError("name must end in A")
        return name

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):

  font-style: italic;
  display: block;
}

.termy {
  /* For right to left languages */
  direction: ltr;
}

.termy [data-termynal] {
  white-space: pre-wrap;
}

.termy .linenos {
  display: none;
}

a.external-link {
  /* For right to left languages */
  direction: ltr;
  display: inline-block;
}

a.external-link::after {
  /* \00A0 is a non-breaking space

    assert response.status_code == 200
    assert response.json() == {
        "item_id": 5,
        "item": {"name": "Foo", "price": 3.0, "description": None, "tax": None},
    }


def test_items_6(client: TestClient):
    response = client.put(
        "/items/6",
        json={
            "item": {
                "name": "Bar",
                "price": 0.2,