如果你在文档中交互并查看响应，即使代码没有给某个 `description` 字段赋值，JSON 响应中仍包含默认值（`null`）：

<div class="screenshot">
<img src="/img/tutorial/separate-openapi-schemas/image02.png">
</div>

这意味着它**总会有值**，只是有时该值可能为 `None`（在 JSON 中是 `null`）。

这也意味着，使用你的 API 的客户端无需检查该值是否存在，他们可以**假设该字段总会存在**，只是有时它会是默认值 `None`。

在 OpenAPI 中描述这一点的方式，是把该字段标记为**必填**，因为它总会存在。

因此，一个模型的 JSON Schema 会根据它用于**输入还是输出**而有所不同：

- 用于**输入**时，`description` **不是必填**

Zum Beispiel deklariert das obige Modell ein JSON „`object`“ (oder Python-<abbr title="Dictionary – Zuordnungstabelle: In anderen Sprachen auch Hash, Map, Objekt, Assoziatives Array genannt">`dict`</abbr>) wie dieses:

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

						if err != nil {
							return err
						}
						// Quote string...
						b, _ := json.Marshal(file.Name)
						b2, err := decode(r, file.Name)
						if err != nil {
							return err
						}
						var tmp map[string]any
						if err := json.Unmarshal(b2, &tmp); err == nil {
							if b3, err := json.Marshal(tmp); err == nil {
								b2 = b3
							}
						}

def test_raw_data_sent_without_json_encoding(client: TestClient):
    """raw_data is sent as-is, not JSON-encoded."""
    response = client.get("/items/stream-raw")
    assert response.status_code == 200
    text = response.text

    # raw_data should appear without JSON quotes
    assert "data: plain text without quotes\n" in text
    # Not JSON-quoted
    assert 'data: "plain text without quotes"' not in text

import com.google.api.client.http.HttpTransport;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.JsonParser;
import com.google.api.client.json.JsonToken;
import com.google.api.client.json.gson.GsonFactory;
import com.google.common.io.BaseEncoding;
import com.google.common.io.BaseEncoding.DecodingException;

	getNetInfoRPC                  = grid.NewSingleHandler[*grid.MSS, *grid.JSON[madmin.NetInfo]](grid.HandlerGetNetInfo, grid.NewMSS, madminNetInfo.NewJSON)
	getOSInfoRPC                   = grid.NewSingleHandler[*grid.MSS, *grid.JSON[madmin.OSInfo]](grid.HandlerGetOSInfo, grid.NewMSS, madminOSInfo.NewJSON)
	getPartitionsRPC               = grid.NewSingleHandler[*grid.MSS, *grid.JSON[madmin.Partitions]](grid.HandlerGetPartitions, grid.NewMSS, madminPartitions.NewJSON)

{* ../../docs_src/server_sent_events/tutorial002_py310.py hl[4,26] *}

El campo `data` siempre se codifica como JSON. Puedes pasar cualquier valor que pueda serializarse como JSON, incluidos modelos de Pydantic.

## Datos sin procesar { #raw-data }

Si necesitas enviar datos **sin** codificarlos a JSON, usa `raw_data` en lugar de `data`.

<div class="screenshot">
<img src="/img/tutorial/separate-openapi-schemas/image02.png">
</div>

Esto significa que **siempre tendrá un valor**, solo que a veces el valor podría ser `None` (o `null` en JSON).

{* ../../docs_src/server_sent_events/tutorial002_py310.py hl[4,26] *}

The `data` field is always encoded as JSON. You can pass any value that can be serialized as JSON, including Pydantic models.

## Raw Data { #raw-data }

If you need to send data **without** JSON encoding, use `raw_data` instead of `data`.

<div class="screenshot">
<img src="/img/tutorial/separate-openapi-schemas/image02.png">
</div>

Isso significa que ele **sempre terá um valor**, só que às vezes o valor pode ser `None` (ou `null` em termos de JSON).