It might also help avoid confusion for new developers that see an unused parameter in your code and could think it's unnecessary.

///

/// info

In this example we use invented custom headers `X-Key` and `X-Token`.

But in real cases, when implementing security, you would get more benefits from using the integrated [Security utilities (the next chapter)](../security/index.md){.internal-link target=_blank}.

///

///

## Add custom headers { #add-custom-headers }

There are some situations in where it's useful to be able to add custom headers to the HTTP error. For example, for some types of security.

You probably won't need to use it directly in your code.

But in case you needed it for an advanced scenario, you can add custom headers:

{* ../../docs_src/handling_errors/tutorial002_py39.py hl[14] *}

* <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/X-Forwarded-For" class="external-link" target="_blank">X-Forwarded-For</a>
* <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/X-Forwarded-Proto" class="external-link" target="_blank">X-Forwarded-Proto</a>
* <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/X-Forwarded-Host" class="external-link" target="_blank">X-Forwarded-Host</a>

## Version 4.9.2

_2021-09-30_

 *  Fix: Don't include potentially-sensitive header values in `Headers.toString()` or exceptions.
    This applies to `Authorization`, `Cookie`, `Proxy-Authorization`, and `Set-Cookie` headers.
 *  Fix: Don't crash with an `InaccessibleObjectException` when running on JDK17+ with strong
    encapsulation enabled.

Mas lembre-se que quando você importa `Query`, `Path`, `Header`, e outras de `fastapi`, elas são na verdade funções que retornam classes especiais.

///

/// info | Informação

Para declarar headers, você precisa usar `Header`, caso contrário, os parâmetros seriam interpretados como parâmetros de consulta.

///

## Conversão automática { #automatic-conversion }

		# Write object back to S3 Object Lambda
		# response sends the transformed data
		# back to MinIO and then to the user
		resp = make_response(transformed_object, 200)
		resp.headers['x-amz-request-route'] = request_route
		resp.headers['x-amz-request-token'] = request_token
		return resp

	else:
		abort(400)

if __name__ == '__main__':
	app.run()
```

            {"Hidden-Header": "somevalue"},
            200,
            {"hidden_header": "somevalue"},
        ),
    ],
)
def test_hidden_header(path, headers, expected_status, expected_response):
    client = TestClient(app)
    response = client.get(path, headers=headers)
    assert response.status_code == expected_status
    assert response.json() == expected_response


def test_hidden_path():

    client = TestClient(mod.app)
    return client


def test_header_param_model(client: TestClient):
    response = client.get(
        "/items/",
        headers=[
            ("save_data", "true"),
            ("if_modified_since", "yesterday"),
            ("traceparent", "123"),
            ("x_tag", "one"),
            ("x_tag", "two"),
        ],
    )

        try (ResponseBody responseBody = response.body()) {
          if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);

          Headers responseHeaders = response.headers();
          for (int i = 0, size = responseHeaders.size(); i < size; i++) {
            System.out.println(responseHeaders.name(i) + ": " + responseHeaders.value(i));
          }

    return {"item_id": item_id, "item": item}


@app.head("/items/{item_id}")
def head_item(item_id: str):
    return JSONResponse(None, headers={"x-fastapi-item-id": item_id})


@app.options("/items/{item_id}")
def options_item(item_id: str):
    return JSONResponse(None, headers={"x-fastapi-item-id": item_id})


@app.patch("/items/{item_id}")
def patch_item(item_id: str, item: Item):