from fastapi import Body, FastAPI
from pydantic import BaseModel

app = FastAPI()


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


class User(BaseModel):
    username: str
    full_name: str | None = None


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item, user: User, importance: int = Body()):

```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
}
```

## Als Parameter deklarieren { #declare-it-as-a-parameter }

{* ../../docs_src/body_nested_models/tutorial004_py310.py hl[18] *}

Isso significa que o **FastAPI** vai esperar um corpo similar à:

```JSON
{
    "name": "Foo",
    "description": "The pretender",
    "price": 42.0,
    "tax": 3.2,
    "tags": ["rock", "metal", "bar"],
    "image": {
        "url": "http://example.com/baz.jpg",
        "name": "The Foo live"
    }
}
```

SSE는 서버에서 클라이언트로 HTTP를 통해 데이터를 스트리밍하기 위한 표준입니다.

각 이벤트는 `data`, `event`, `id`, `retry`와 같은 "필드"를 가진 작은 텍스트 블록이며, 빈 줄로 구분됩니다.

다음과 같습니다:

```
data: {"name": "Portal Gun", "price": 999.99}

data: {"name": "Plumbus", "price": 32.99}

```

SSE는 AI 채팅 스트리밍, 실시간 알림, 로그와 관측성, 그리고 서버가 클라이언트로 업데이트를 푸시하는 여러 경우에 흔히 사용됩니다.

/// tip | 팁

{* ../../docs_src/body_nested_models/tutorial004_py310.py hl[18] *}

Це означатиме, що  **FastAPI**  очікуватиме тіло запиту такого вигляду:

```JSON
{
    "name": "Foo",
    "description": "The pretender",
    "price": 42.0,
    "tax": 3.2,
    "tags": ["rock", "metal", "bar"],
    "image": {
        "url": "http://example.com/baz.jpg",
        "name": "The Foo live"
    }
}
```

So, if you send a request to that *path operation* for the item with ID `foo`, the response (not including default values) will be:

```JSON
{
    "name": "Foo",
    "price": 50.2
}
```

/// info

You can also use:

* `response_model_exclude_defaults=True`
* `response_model_exclude_none=True`

Então, se você enviar uma solicitação para essa *operação de rota* para o item com ID `foo`, a resposta (sem incluir valores padrão) será:

```JSON
{
    "name": "Foo",
    "price": 50.2
}
```

/// info | Informação

Você também pode usar:

* `response_model_exclude_defaults=True`
* `response_model_exclude_none=True`

Chaque événement est un petit bloc de texte avec des « champs » comme `data`, `event`, `id` et `retry`, séparés par des lignes vides.

Cela ressemble à ceci :

```
data: {"name": "Portal Gun", "price": 999.99}

data: {"name": "Plumbus", "price": 32.99}

```

Les SSE sont couramment utilisés pour le streaming de chat IA, les notifications en direct, les journaux et l’observabilité, et d’autres cas où le serveur envoie des mises à jour au client.

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

...como `description` e `tax` são opcionais (com um valor padrão de `None`), esse JSON "`object`" também é válido:

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

## Declare como um parâmetro { #declare-it-as-a-parameter }

You will also get autocompletion for the payload to send:

<img src="/img/tutorial/generate-clients/image03.png">

/// tip

Notice the autocompletion for `name` and `price`, that was defined in the FastAPI application, in the `Item` model.

///

You will have inline errors for the data that you send:

<img src="/img/tutorial/generate-clients/image04.png">