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

...dado que `description` y `tax` son opcionales (con un valor por defecto de `None`), este “`object`” JSON también sería válido:

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

## Decláralo como un parámetro { #declare-it-as-a-parameter }

```JSON hl_lines="2"
{
    "item": {
        "name": "Foo",
        "description": "The pretender",
        "price": 42.0,
        "tax": 3.2
    }
}
```

以下の代わりに:

```JSON
{
    "name": "Foo",
    "description": "The pretender",
    "price": 42.0,
    "tax": 3.2
}
```

## まとめ { #recap }

Her olay, aralarında boş satırlar bulunan ve `data`, `event`, `id` ve `retry` gibi "alanlar" içeren küçük bir metin bloğudur.

Şuna benzer:

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

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

```

Каждое событие — это небольшой текстовый блок с «полями», такими как `data`, `event`, `id` и `retry`, разделёнными пустыми строками.

Это выглядит так:

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

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

```

SSE часто используют для стриминга ответов ИИ в чатах, живых уведомлений, логов и наблюдаемости, а также в других случаях, когда сервер «проталкивает» обновления клиенту.

from fastapi import FastAPI
from pydantic import BaseModel


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


app = FastAPI()


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

from fastapi import FastAPI, status
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None
    tags: set[str] = set()


@app.post("/items/", status_code=status.HTTP_201_CREATED)
async def create_item(item: Item) -> Item:

    public void test_evaluate_withSpecialCharacters() {
        String template = "Price: $${price} (with ${discount}% off)";
        Map<String, Object> paramMap = new HashMap<>();
        paramMap.put("price", "100");
        paramMap.put("discount", "20");

        Object result = scriptEngine.evaluate(template, paramMap);
        assertEquals("Price: $100 (with 20% off)", result);
    }

from pydantic import BaseModel, Field

app = FastAPI()


class Item(BaseModel):
    name: str = Field(examples=["Foo"])
    description: str | None = Field(default=None, examples=["A very nice Item"])
    price: float = Field(examples=[35.4])
    tax: float | None = Field(default=None, examples=[3.2])


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

SSE 是一種透過 HTTP 從伺服器向用戶端串流傳送資料的標準。

每個事件都是一個小型文字區塊，包含 `data`、`event`、`id` 和 `retry` 等「欄位」，並以空白行分隔。

看起來像這樣：

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

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

```

SSE 常用於 AI 聊天串流、即時通知、日誌與可觀察性，以及其他由伺服器主動推送更新給用戶端的情境。

/// tip

如果你要串流二進位資料，例如影片或音訊，請參考進階指南：[串流資料](../advanced/stream-data.md)。

///

from typing import Annotated

from fastapi import FastAPI, Path
from pydantic import BaseModel

app = FastAPI()


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


@app.put("/items/{item_id}")
async def update_item(
    item_id: Annotated[int, Path(title="The ID of the item to get", ge=0, le=1000)],
    q: str | None = None,
    item: Item | None = None,