```JSON
{
    "message": "Hello World",
    "root_path": "/api/v1"
}
```

### Setting the `root_path` in the FastAPI app

Alternatively, if you don't have a way to provide a command line option like `--root-path` or equivalent, you can set the `root_path` parameter when creating your FastAPI app:

```Python hl_lines="3"
{!../../../docs_src/behind_a_proxy/tutorial002.py!}
```

These features are what Marshmallow was built to provide. It is a great library, and I have used it a lot before.

But it was created before there existed Python type hints. So, to define every <abbr title="the definition of how data should be formed">schema</abbr> you need to use specific utils and classes provided by Marshmallow.

!!! check "Inspired **FastAPI** to"
    Use code to define "schemas" that provide data types and validation, automatically.

* <a href="https://tartiflette.io/" class="external-link" target="_blank">Tartiflette</a>
    * With <a href="https://tartiflette.github.io/tartiflette-asgi/" class="external-link" target="_blank">Tartiflette ASGI</a> to provide ASGI integration
* <a href="https://graphene-python.org/" class="external-link" target="_blank">Graphene</a>

And it shows their true commitment to FastAPI and its **community** (you), as they not only want to provide you a **good service** but also want to make sure you have a **good and healthy framework**, FastAPI. 🙇

!!! tip "Dica"
    O `shutdown` aconteceria quando você estivesse **encerrando** a aplicação.

    Talvez você precise inicializar uma nova versão, ou apenas cansou de executá-la. 🤷

### Função _lifespan_

A primeira coisa a notar, é que estamos definindo uma função assíncrona com `yield`. Isso é muito semelhante à Dependências com `yield`.

Há diversas situações em que você precisa notificar um erro a um cliente que está utilizando a sua API.

Esse cliente pode ser um browser com um frontend, o código de outra pessoa, um dispositivo IoT, etc.

Pode ser que você precise comunicar ao cliente que:

* O cliente não tem direitos para realizar aquela operação.
* O cliente não tem acesso aquele recurso.
* O item que o cliente está tentando acessar não existe.
* etc.

And it shows their true commitment to FastAPI and its **community** (you), as they not only want to provide you a **good service** but also want to make sure you have a **good and healthy framework**, FastAPI. 🙇

You might want to try their services and follow their guides:

In many cases they will only copy a fragment of the code, but that's not enough to **reproduce the problem**.

    * It depends on the `query_extractor`, and assigns the value returned by it to the parameter `q`.
* It also declares an optional `last_query` cookie, as a `str`.
    * If the user didn't provide any query `q`, we use the last query used, which we saved to a cookie before.

## Use the dependency

Then we can use the dependency with:

=== "Python 3.10+"

    ```Python hl_lines="23"

!!! check
    OpenAPI specifies that each *path operation* requires a response description.

    So, if you don't provide one, **FastAPI** will automatically generate one of "Successful response".

<img src="/img/tutorial/path-operation-configuration/image03.png">

## Deprecate a *path operation*