from fastapi import FastAPI, Response

        app = FastAPI()

        @app.head("/items/", status_code=204)
        def get_items_headers(response: Response):
            response.headers["X-Cat-Dog"] = "Alone in the world"
        ```
        """
        return self.router.head(
            path,
            response_model=response_model,
            status_code=status_code,

contentType)&&v.setRequestHeader("Content-Type",k.contentType),v.setRequestHeader("Accept",k.dataTypes[0]&&k.accepts[k.dataTypes[0]]?k.accepts[k.dataTypes[0]]+("*"!==k.dataTypes[0]?", "+pc+"; q=0.01":""):k.accepts["*"]);for(j in k.headers)v.setRequestHeader(j,k.headers[j]);if(k.beforeSend&&(k.beforeSend.call(l,v,k)===!1||2===t))return v.abort();u="abort";for(j in{success:1,error:1,complete:1})v[j](k[j]);if(c=sc(oc,k,b,v)){v.readyState=1,i&&m.trigger("ajaxSend",[v,k]),k.async&&k.timeout>0&&(g=set...

<%@page pageEncoding="UTF-8" contentType="text/html; charset=UTF-8"%>
<nav class="main-header navbar navbar-expand navbar-dark navbar-secondary">
	<ul class="navbar-nav">
		<li class="nav-item">
			<a class="nav-link" data-widget="pushmenu" href="#">
				<em class="fas fa-bars">
				<span class="sr-only"><la:message
						key="labels.admin_toggle_navi" /></span>
			</a>
		</li>
	</ul>
	<ul class="navbar-nav ml-auto">
		<c:if test="${eoled}">

Shinsuke Sugaya <******@****.***> 1390632593 +0900

	return messWith("crc32-not-streamed.zip", func(b []byte) {
		// Corrupt foo.txt's final crc32 byte, in both
		// the file header and TOC. (0x7e -> 0x7f)
		b[0x11]++
		b[0x9d]++

		// TODO(bradfitz): add a new test that only corrupts
		// one of these values, and verify that that's also an
		// error. Currently, the reader code doesn't verify the
		// fileheader and TOC's crc32 match if they're both

const maxDocumentSize = 10 << 20

// Reader - JSON record reader for S3Select.
type Reader struct {
	args       *ReaderArgs
	decoder    *jstream.Decoder
	valueCh    chan *jstream.MetaValue
	readCloser io.ReadCloser
}

// Read - reads single record.
func (r *Reader) Read(dst sql.Record) (sql.Record, error) {
	v, ok := <-r.valueCh
	if !ok {

            data: Union[str, None] = Header(
                default=None,
                example="header1",
            ),
        ):
            return data

    @app.get("/header_examples/")
    def header_examples(
        data: Union[str, None] = Header(
            default=None,
            examples=[
                "header1",
                "header2",
            ],
        ),
    ):

# Header-параметры

Вы можете определить параметры заголовка таким же образом, как вы определяете параметры `Query`, `Path` и `Cookie`.

## Импорт `Header`

Сперва импортируйте `Header`:

//// tab | Python 3.10+

```Python hl_lines="3"
{!> ../../docs_src/header_params/tutorial001_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="3"
{!> ../../docs_src/header_params/tutorial001_an_py39.py!}
```

```

////

/// note | "技术细节"

`Header` 是 `Path`、`Query`、`Cookie` 的**兄弟类**，都继承自共用的 `Param` 类。

注意，从 `fastapi` 导入的 `Query`、`Path`、`Header` 等对象，实际上是返回特殊类的函数。

///

/// info | "说明"

必须使用 `Header` 声明 header 参数，否则该参数会被解释为查询参数。

///

## 自动转换

`Header` 比 `Path`、`Query` 和 `Cookie` 提供了更多功能。

大部分标准请求头用**连字符**分隔，即**减号**（`-`）。

  // +optional
  optional string scheme = 4;

  // Custom headers to set in the request. HTTP allows repeated headers.
  // +optional
  repeated HTTPHeader httpHeaders = 5;
}

// HTTPHeader describes a custom header to be used in HTTP probes
message HTTPHeader {
  // The header field name
  optional string name = 1;

  // The header field value
  optional string value = 2;
}