## 自定义 `PNGStreamingResponse` { #a-custom-pngstreamingresponse }

在上面的示例中，虽然按字节流式传输了数据，但响应没有 `Content-Type` 头，因此客户端不知道接收到的数据类型。

你可以创建 `StreamingResponse` 的自定义子类，将 `Content-Type` 头设置为你要流式传输的数据类型。

例如，你可以创建一个 `PNGStreamingResponse`，通过 `media_type` 属性把 `Content-Type` 头设置为 `image/png`：

{* ../../docs_src/stream_data/tutorial002_py310.py ln[6,19:20] hl[20] *}

     *
     * @param objectName the name/path for the object
     * @param inputStream the input stream of data to upload
     * @param size the size of the data in bytes
     * @param contentType the MIME type of the content
     */
    void uploadObject(String objectName, InputStream inputStream, long size, String contentType);

    /**
     * Downloads an object from storage.
     *

///

Затем Pydantic декодирует строку base64 и передаст вам исходные байты в поле `data` модели.

Вы получите такой HTTP-ответ:

```json
{
  "description": "Some data",
  "content": "hello"
}
```

## Pydantic `bytes` для выходных данных { #pydantic-bytes-for-output-data }

/**
 * Base class for testers of classes (including {@link Collection} and {@link java.util.Map Map})
 * that contain elements.
 *
 * @param <C> the type of the container
 * @param <E> the type of the container's contents
 * @author George van den Driessche
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")

        assertNull(entries[0].getName());
        assertEquals(8, entries[0].getType()); // TYPE_SHARE constant value

        assertInstanceOf(SmbShareInfo.class, entries[1]);
        assertEquals("valid_share", entries[1].getName());
        assertEquals(8, entries[1].getType()); // TYPE_SHARE constant value
    }

    @Test
    @DisplayName("DCE/RPC flags should be set correctly")
    void testDcerpcFlags() {

BSize��EcIndex�EcDist�
�CSumAlgo
�PartNums�
�PartETags��PartSizes��	ը�PartASizes��	ը�Size�	ը�MTime�����çMetaSys��x-minio-internal-replica-status�REPLICA�"x-minio-internal-replica-timestamp�2022-03-20T15:15:01.584169645Z�MetaUsr��content-type�application/octet-stream�x-amz-storage-class�STANDARD�X-Amz-Replication-Status�REPLICA�etag� 9587ddd31fead633830366f45d221d56�;��...

    /**
     * Connect to a remote RDMA endpoint
     *
     * @param hostname remote hostname or IP address
     * @param port remote port number
     * @return established RDMA connection
     * @throws IOException if connection fails
     */
    RdmaConnection connect(String hostname, int port) throws IOException;

    /**

class Item(BaseModel):
    id: str
    value: str


app = FastAPI()


@app.get(
    "/items/{item_id}",
    response_model=Item,
    responses={
        200: {
            "content": {"image/png": {}},
            "description": "Return the JSON item or an image.",
        }
    },
)
async def read_item(item_id: str, img: bool | None = None):
    if img:

		},
		{
			Name:    "idx_user_indices_name5",
			Class:   "FULLTEXT",
			Comment: "hello , world",
			Where:   "age > 10",
			Fields:  []schema.IndexOption{{Field: &schema.Field{Name: "Name5"}}},
		},
		{
			Name:    "profile",
			Comment: "hello , world",
			Where:   "age > 10",
			Option:  "WITH PARSER parser_name",

		config.HelpKV{
			Key:         httpTimeout,
			Description: `defines the maximum duration for each http request`,
			Optional:    true,
			Type:        "duration",
		},
		config.HelpKV{
			Key:         config.Comment,
			Description: config.DefaultComment,
			Optional:    true,
			Type:        "sentence",
		},
	}

	HelpWebhook = config.HelpKVS{
		config.HelpKV{
			Key:         Endpoint,