from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


app = FastAPI()


@app.post("/items/")
async def create_item(item: Item):

                ),
                PerformanceTestCoverage(1, PerformanceTestType.PER_COMMIT, Os.LINUX),
                "Description",
                "performance",
                listOf("largeTestProject", "smallTestProject"),
                2,
                extraParameters = "extraParameters",
            )

        assertEquals(

  private Enums() {}

  /**
   * Returns the {@link Field} in which {@code enumValue} is defined. For example, to get the {@code
   * Description} annotation on the {@code GOLF} constant of enum {@code Sport}, use {@code
   * Enums.getField(Sport.GOLF).getAnnotation(Description.class)}.
   *
   * @since 12.0
   */
  public static Field getField(Enum<?> enumValue) {
    Class<?>
        clazz = enumValue.getDeclaringClass();

from fastapi import FastAPI
from fastapi.encoders import jsonable_encoder
from pydantic import BaseModel

fake_db = {}


class Item(BaseModel):
    title: str
    timestamp: datetime
    description: str | None = None


app = FastAPI()


@app.put("/items/{id}")
def update_item(id: str, item: Item):
    json_compatible_item_data = jsonable_encoder(item)

Например, модель выше описывает такой JSON "объект" (или Python `dict`):

```JSON
{
    "name": "Foo",
    "description": "An optional description",
    "price": 45.2,
    "tax": 3.5
}
```

...так как `description` и `tax` являются необязательными (со значением по умолчанию `None`), такой JSON "объект" тоже будет корректным:

```JSON
{
    "name": "Foo",
    "price": 45.2

from typing import Annotated, Union

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


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    size: float


app = FastAPI()


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

        "info": {"title": "FastAPI", "version": "0.1.0"},
        "paths": {
            "/": {
                "get": {
                    "responses": {
                        "200": {
                            "description": "Successful Response",
                            "content": {"application/json": {"schema": {}}},
                        }
                    },
                    "summary": "Read Main",

```JSON
{
    "name": "Foo",
    "description": "An optional description",
    "price": 45.2,
    "tax": 3.5
}
```

Da `description` und `tax` optional sind (mit `None` als Defaultwert), wäre folgendes JSON „`object`“ auch gültig:

```JSON
{
    "name": "Foo",
    "price": 45.2
}
```

与声明查询参数一样，包含默认值的模型属性是可选的，否则就是必选的。默认值为 `None` 的模型属性也是可选的。

例如，上述模型声明如下 JSON **对象**（即 Python **字典**）：

```JSON
{
    "name": "Foo",
    "description": "An optional description",
    "price": 45.2,
    "tax": 3.5
}
```

……由于 `description` 和 `tax` 是可选的（默认值为 `None`），下面的 JSON **对象**也有效：

```JSON
{
    "name": "Foo",
    "price": 45.2
}
```

## 声明请求体参数

    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"}
        )