**FastAPI** **extraerá** los datos para **cada campo** de los **headers** en el request y te dará el modelo Pydantic que definiste.

## Revisa la Documentación { #check-the-docs }

Puedes ver los headers requeridos en la interfaz de documentación en `/docs`:

<div class="screenshot">
<img src="/img/tutorial/header-param-models/image01.png">
</div>

## Prohibir Headers Extra { #forbid-extra-headers }

  fun writeRequest(
    headers: Headers,
    requestLine: String,
  ) {
    check(state == STATE_IDLE) { "state: $state" }
    socket.sink.writeUtf8(requestLine).writeUtf8("\r\n")
    for (i in 0 until headers.size) {
      socket.sink
        .writeUtf8(headers.name(i))
        .writeUtf8(": ")
        .writeUtf8(headers.value(i))
        .writeUtf8("\r\n")
    }

  }

  @Test
  fun headers() {
    var headers: Headers = headersOf("", "")
    headers = mapOf("" to "").toHeaders()
    val get: String? = headers[""]
    val date: Date? = headers.getDate("")
    val instant: Instant? = headers.getInstant("")
    val size: Int = headers.size
    val name: String = headers.name(0)
    val value: String = headers.value(0)
    val names: Set<String> = headers.names()

    val body = "hello".toRequestBody()
    val headers = headersOf("User-Agent", "RequestTest")
    val method = "PUT"
    val request =
      Request(
        url = url,
        headers = headers,
        method = method,
        body = body,
      )
    assertThat(request.url).isEqualTo(url)
    assertThat(request.headers).isEqualTo(headers)
    assertThat(request.method).isEqualTo(method)

    val partAbc = parts.nextPart()!!
    assertThat(partAbc.headers).isEqualTo(
      headersOf(
        "Content-Type",
        "text/plain; charset=utf-8",
        "Content-ID",
        "abc",
      ),
    )
    assertThat(partAbc.body.readUtf8()).isEqualTo("abcd\r\nefgh")

    val partIjk = parts.nextPart()!!
    assertThat(partIjk.headers).isEqualTo(
      headersOf(
        "Content-Type",

            - set_cookie
            - delete_cookie

::: fastapi.responses.StreamingResponse
    options:
        members:
            - body_iterator
            - charset
            - status_code
            - media_type
            - body
            - background
            - raw_headers
            - render
            - init_headers
            - headers
            - set_cookie

	"X-Minio-Replication-Encrypted-Multipart",
	"X-Minio-Replication-Actual-Object-Size",
	ReplicationSsecChecksumHeader,
	// Add more supported headers here.
}

// mapping of internal headers to allowed replication headers
var validSSEReplicationHeaders = map[string]string{
	"X-Minio-Internal-Server-Side-Encryption-Sealed-Key":     "X-Minio-Replication-Server-Side-Encryption-Sealed-Key",

* `allow_headers` - Una lista de headers de request HTTP que deberían estar soportados para requests cross-origin. Por defecto es `[]`. Puedes usar `['*']` para permitir todos los headers. Los headers `Accept`, `Accept-Language`, `Content-Language` y `Content-Type` siempre están permitidos para [requests CORS simples](https://developer.mozilla.org/en-US/docs/Web/HT...

from fastapi import FastAPI
from fastapi.responses import JSONResponse

app = FastAPI()


@app.get("/headers/")
def get_headers():
    content = {"message": "Hello World"}
    headers = {"X-Cat-Dog": "alone in the world", "Content-Language": "en-US"}

			continue
		}
		t.Run(fmt.Sprintf("%d-locks", locks), func(t *testing.T) {
			// Number of readers per lock...
			for _, readers := range []int{1, 10, 100} {
				if locks > 1000 && readers > 1 {
					continue
				}
				if testing.Short() && readers > 10 {
					continue
				}
				t.Run(fmt.Sprintf("%d-read", readers), func(t *testing.T) {
					l := newLocker()
					for range locks {
						var tmp [16]byte