## Caso de uso { #use-case }

Vamos começar com um exemplo de **caso de uso** e então ver como resolvê-lo com isso.

 *
 * @since 4.0.0
 */
@Experimental
public interface VersionParser extends Service {

    /**
     * Parses the specified version string, for example "1.0".
     *
     * @param version the version string to parse, must not be {@code null}
     * @return the parsed version, never {@code null}

Em alguns casos, você pode querer sobrescrever a lógica usada pelas classes `Request` e `APIRoute`.

Em particular, isso pode ser uma boa alternativa para uma lógica em um middleware.

Por exemplo, se você quiser ler ou manipular o corpo da requisição antes que ele seja processado pela sua aplicação.

/// danger | Cuidado

Isso é um recurso "avançado".

That's why in this example we have to declare it in the `response_model` parameter.

...but continue reading below to see how to overcome that.

## Return Type and Data Filtering { #return-type-and-data-filtering }

User-agent: Crawler
Disallow: /aaa

User-agent: Crawler/1.0
Disallow: /bbb

User-agent: Crawler/2.0
Disallow: /ccc

User-agent: Hoge Crawler
Disallow: /ddd

sitemap: http://www.example.com/sitmap.xml

      Route(
        factory.newAddress(uriHost = "example.com", uriPort = 1003),
        Proxy.NO_PROXY,
        InetSocketAddress(ipv4Address, 1003),
      ).toString(),
    ).isEqualTo("example.com at 1.2.3.4:1003")
    assertThat(
      Route(
        factory.newAddress(uriHost = "example.com", uriPort = 1003),
        Proxy(Proxy.Type.HTTP, InetSocketAddress.createUnresolved("proxy.example.com", 1003)),

<?xml version="1.0" encoding="UTF-8"?>
<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
   <sitemap>
      <loc>http://www.example.com/sitemap1.xml.gz</loc>
      <lastmod>2004-10-01T18:23:17+00:00</lastmod>
   </sitemap>
   <sitemap>
      <loc>http://www.example.com/sitemap2.xml.gz</loc>
      <lastmod>2005-01-01</lastmod>
   </sitemap>

    monkeypatch.setenv("ADMIN_EMAIL", "admin@example.com")
    mod = importlib.import_module(f"docs_src.settings.{request.param}")
    return mod.app


def test_settings(app):
    client = TestClient(app)
    response = client.get("/info")
    assert response.status_code == 200, response.text
    assert response.json() == {
        "app_name": "Awesome API",
        "admin_email": "admin@example.com",
        "items_per_user": 50,

def get_settings_override():
    return Settings(admin_email="testing_admin@example.com")


app.dependency_overrides[get_settings] = get_settings_override


def test_app():
    response = client.get("/info")
    data = response.json()
    assert data == {
        "app_name": "Awesome API",
        "admin_email": "testing_admin@example.com",
        "items_per_user": 50,

FastAPI converts the configurations to **JSON** to make them compatible with JavaScript, as that's what Swagger UI needs.

## Disable Syntax Highlighting { #disable-syntax-highlighting }

For example, you could disable syntax highlighting in Swagger UI.

Without changing the settings, syntax highlighting is enabled by default:

<img src="/img/tutorial/extending-openapi/image02.png">