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

## Заборонити додаткові заголовки { #forbid-extra-headers }

У деяких особливих випадках (ймовірно, не дуже поширених) ви можете захотіти **обмежити** заголовки, які хочете отримати.

Ви можете використати конфігурацію моделі Pydantic, щоб `заборонити` будь-які `додаткові` поля:

api.search.accept.referers=
# Whether to enable scroll for API search.
api.search.scroll=false
# Headers for API JSON response.
api.json.response.headers=Referrer-Policy:strict-origin-when-cross-origin
# Whether to include exceptions in API JSON response.
api.json.response.exception.included=false
# Headers for API GSA response.
api.gsa.response.headers=Referrer-Policy:strict-origin-when-cross-origin
# Whether to include exceptions in API GSA response.

        )

    tasks.add_task(bg, state)
    return state


@app.middleware("http")
async def middleware(request, call_next):
    response: StreamingResponse = await call_next(request)
    response.headers["x-state"] = json.dumps(state.copy())
    return response


client = TestClient(app)


def test_async_state():
    assert state["/async"] == "asyncgen not started"
    response = client.get("/async")

	t.Run(fmt.Sprintf("%d-%d-%d", gomaxprocs, numReaders, numIterations), func(t *testing.T) {
		resource := "test"
		runtime.GOMAXPROCS(gomaxprocs)
		// Number of active readers + 10000 * number of active writers.
		var activity int32
		cdone := make(chan bool)
		go writer(resource, numIterations, &activity, cdone)
		var i int
		for i = 0; i < numReaders/2; i++ {

    assertThat(cacheControl.onlyIfCached).isTrue()
    assertThat(cacheControl.noTransform).isTrue()
    assertThat(cacheControl.immutable).isTrue()

    // These members are accessible to response headers only.
    assertThat(cacheControl.sMaxAgeSeconds).isEqualTo(-1)
    assertThat(cacheControl.isPrivate).isFalse()
    assertThat(cacheControl.isPublic).isFalse()
    assertThat(cacheControl.mustRevalidate).isFalse()
  }

  }

  @Test
  fun worksIfTrailersSet() {
    val response =
      newResponse("".toResponseBody()) {
        trailers(
          object : TrailersSource {
            override fun get() = Headers.headersOf("a", "b")
          },
        )
      }

    assertThat(response.trailers()["a"]).isEqualTo("b")
  }

  @Test fun peekAfterReadingResponse() {
    val response = newResponse(responseBody("abc"))

					"GOLANG.pkg":     "tar",
				},
			}, nil},
			testClose{nil},
		},
	}, {
		// Craft a theoretically valid PAX archive with global headers.
		// The GNU and BSD tar tools do not parse these the same way.
		//
		// BSD tar v3.1.2 parses and ignores all global headers;
		// the behavior is verified by researching the source code.
		//
		//	$ bsdtar -tvf pax-global-records.tar

	objInfo, err := getObjectInfo(ctx, bucket, object, gopts)
	if err != nil {
		// Versioning enabled quite possibly object is deleted might be delete-marker
		// if present set the headers, no idea why AWS S3 sets these headers.
		if objInfo.VersionID != "" && objInfo.DeleteMarker {
			w.Header()[xhttp.AmzVersionID] = []string{objInfo.VersionID}
			w.Header()[xhttp.AmzDeleteMarker] = []string{strconv.FormatBool(objInfo.DeleteMarker)}

expect object OkHttp {
  /**
   * This is a string like "5.0.0", "5.0.0-alpha.762", or "5.3.0-SNAPSHOT" indicating the version of
   * OkHttp in the current runtime. Use this to include the OkHttp version in custom `User-Agent`
   * headers.
   *
   * Official OkHttp releases follow [semantic versioning][semver]. Versions with the `-SNAPSHOT`
   * qualifier are not unique and should only be used in development environments. If you create

 */
package okhttp3

import assertk.assertThat
import assertk.assertions.isEqualTo
import java.io.IOException
import java.nio.charset.StandardCharsets
import kotlin.test.assertFailsWith
import okhttp3.Headers.Companion.headersOf
import okhttp3.MediaType.Companion.toMediaType
import okhttp3.MediaType.Companion.toMediaTypeOrNull
import okhttp3.RequestBody.Companion.toRequestBody
import okio.Buffer
import okio.BufferedSink