```Python
def get_settings():
    return Settings()
```

we would create that object for each request, and we would be reading the `.env` file for each request. ⚠️

But as we are using the `@lru_cache` decorator on top, the `Settings` object will be created only once, the first time it's called. ✔️

{* ../../docs_src/settings/app03_an_py39/main.py hl[1,11] *}

* **Uitbreidbaar**:
    * Met Pydantic kunnen op maat gemaakte datatypen worden gedefinieerd of je kunt validatie uitbreiden met methoden op een model dat is ingericht met de decorator validator.

E a parte posterior do `yield` irá executar **após** a aplicação ser encerrada.

### Gerenciador de Contexto Assíncrono

Se você verificar, a função está decorada com um `@asynccontextmanager`.

Que converte a função em algo chamado de "**Gerenciador de Contexto Assíncrono**".

{* ../../docs_src/events/tutorial003.py hl[1,13] *}

## Additional Response with `model` { #additional-response-with-model }

You can pass to your *path operation decorators* a parameter `responses`.

It receives a `dict`: the keys are status codes for each response (like `200`), and the values are other `dict`s with the information for each of them.

Önemli olan, standart Python türlerini tek bir yerde kullanarak (daha fazla sınıf, dekoratör vb. eklemek yerine), **FastAPI**'nin bizim için işi yapmasını sağlamak.

/// info

Y también incluye un manejador de excepciones predeterminado para ello.

Para sobrescribirlo, importa el `RequestValidationError` y úsalo con `@app.exception_handler(RequestValidationError)` para decorar el manejador de excepciones.

El manejador de excepciones recibirá un `Request` y la excepción.

{* ../../docs_src/handling_errors/tutorial004.py hl[2,14:16] *}

Quando a requisição contém dados inválidos, **FastAPI** internamente lança para o `RequestValidationError`.

Para sobrescrevê-lo, importe o `RequestValidationError` e use-o com o `@app.exception_handler(RequestValidationError)` para decorar o manipulador de exceções.

{* ../../docs_src/handling_errors/tutorial004.py hl[2,14:16] *}

Se você for ao `/items/foo`, em vez de receber o JSON padrão com o erro:

```JSON
{
    "detail": [

 * override one or more methods to modify the behavior of the backing map as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingNavigableMap} forward <i>indiscriminately</i>
 * to the methods of the delegate. For example, overriding {@link #put} alone <i>will not</i> change

 * override one or more methods to modify the behavior of the backing map as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingNavigableMap} forward <i>indiscriminately</i>
 * to the methods of the delegate. For example, overriding {@link #put} alone <i>will not</i> change

Das war's schon.

**Zwei Zeilen**.

Und sie hat die gleiche Form und Struktur wie alle Ihre *Pfadoperation-Funktionen*.

Sie können sie sich als *Pfadoperation-Funktion* ohne den „Dekorator“ (ohne `@app.get("/some-path")`) vorstellen.

Und sie kann alles zurückgeben, was Sie möchten.

In diesem Fall erwartet diese Abhängigkeit:

* Einen optionalen Query-Parameter `q`, der ein `str` ist.