# 响应头

## 使用 `Response` 参数

你可以在你的*路径操作函数*中声明一个`Response`类型的参数（就像你可以为cookies做的那样）。

然后你可以在这个*临时*响应对象中设置头部。
```Python hl_lines="1  7-8"
{!../../../docs_src/response_headers/tutorial002.py!}
```

然后你可以像平常一样返回任何你需要的对象（例如一个`dict`或者一个数据库模型）。如果你声明了一个`response_model`，它仍然会被用来过滤和转换你返回的对象。

**FastAPI**将使用这个临时响应来提取头部（也包括cookies和状态码），并将它们放入包含你返回的值的最终响应中，该响应由任何`response_model`过滤。

你也可以在依赖项中声明`Response`参数，并在其中设置头部（和cookies）。

## 直接返回 `Response`

  }

  /** Accept headers from the network and store them until the client calls [takeHeaders]. */
  fun receiveHeaders(
    headers: Headers,
    inFinished: Boolean,
  ) {
    lock.assertNotHeld()

    val open: Boolean
    this.withLock {
      if (!hasResponseHeaders ||
        headers[Header.RESPONSE_STATUS_UTF8] != null ||
        headers[Header.TARGET_METHOD_UTF8] != null
      ) {

            - background
            - raw_headers
            - render
            - init_headers
            - headers
            - set_cookie
            - delete_cookie

::: fastapi.responses.HTMLResponse
    options:
        members:
            - charset
            - status_code
            - media_type
            - body
            - background
            - raw_headers
            - render

    assertThat(response.protocol).isEqualTo(protocol)
    val logs = testLogHandler.takeAll()
    assertThat(firstFrame(logs, "HEADERS")!!, "header logged")
      .contains("HEADERS       END_HEADERS")
    // While MockWebServer waits to read the client's HEADERS frame before sending the response, it
    // doesn't wait to read the client's DATA frame and may send a DATA frame before the client

  name: String,
  value: String,
) = apply {
  headers[name] = value
}

fun Response.Builder.commonAddHeader(
  name: String,
  value: String,
) = apply {
  headers.add(name, value)
}

fun Response.Builder.commonRemoveHeader(name: String) =
  apply {
    headers.removeAll(name)
  }

fun Response.Builder.commonHeaders(headers: Headers) =
  apply {
    this.headers = headers.newBuilder()

    peer.acceptFrame() // ACK
    peer.acceptFrame() // SYN_STREAM
    peer.sendFrame().headers(false, 3, headerEntries("a", "android"))
    val expectedRequestHeaders =
      listOf(
        Header(Header.TARGET_METHOD, "GET"),
        Header(Header.TARGET_SCHEME, "https"),
        Header(Header.TARGET_AUTHORITY, "squareup.com"),
        Header(Header.TARGET_PATH, "/cached"),
      )

        this.sentRequestMillis = cacheResponse.sentRequestAtMillis
        this.receivedResponseMillis = cacheResponse.receivedResponseAtMillis
        val headers = cacheResponse.headers
        for (i in 0 until headers.size) {
          val fieldName = headers.name(i)
          val value = headers.value(i)
          when {
            fieldName.equals("Date", ignoreCase = true) -> {
              servedDate = value.toHttpDateOrNull()

        length = length.toInt(),
        type = TYPE_CONTINUATION,
        flags = if (byteCount == 0L) FLAG_END_HEADERS else 0,
      )
      sink.write(hpackBuffer, length)
    }
  }

  @Throws(IOException::class)
  fun headers(
    outFinished: Boolean,
    streamId: Int,
    headerBlock: List<Header>,
  ) {
    this.withLock {
      if (closed) throw IOException("closed")

	public final fun addUnsafeNonAscii (Ljava/lang/String;Ljava/lang/String;)Lokhttp3/Headers$Builder;
	public final fun build ()Lokhttp3/Headers;
	public final fun get (Ljava/lang/String;)Ljava/lang/String;
	public final fun removeAll (Ljava/lang/String;)Lokhttp3/Headers$Builder;
	public final fun set (Ljava/lang/String;Ljava/lang/String;)Lokhttp3/Headers$Builder;

    client.listener.assertTextMessage(message)
  }

  @Test
  fun messagesCompressedWhenConfigured() {
    val headers = headersOf("Sec-WebSocket-Extensions", "permessage-deflate")
    client.initWebSocket(random, responseHeaders = headers)
    server.initWebSocket(random, responseHeaders = headers)
    val message = repeat('a', RealWebSocket.DEFAULT_MINIMUM_DEFLATE_SIZE.toInt())
    server.webSocket!!.send(message)