@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}
```

<details markdown="1">
<summary>Ou utilisez <code>async def</code> ...</summary>

Si votre code utilise `async` / `await`, utilisez `async def` :

```Python hl_lines="9  14"
from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")

## Resource Utilization

Your server(s) is (are) a **resource**, you can consume or **utilize**, with your programs, the computation time on the CPUs, and the RAM memory available.

* ♻ Change a `dict()` for `{}` in `fastapi/utils.py`. PR [#3138](https://github.com/tiangolo/fastapi/pull/3138) by [@ShahriyarR](https://github.com/ShahriyarR).
* ♻ Move internal variable for errors in `jsonable_encoder` to put related code closer. PR [#4560](https://github.com/tiangolo/fastapi/pull/4560) by [@GuilleQP](https://github.com/GuilleQP).

That means that any value read in Python from an environment variable will be a `str`, and any conversion to a different type or validation has to be done in code.

## Pydantic `Settings`

Fortunately, Pydantic provides a great utility to handle these settings coming from environment variables with <a href="https://docs.pydantic.dev/latest/usage/pydantic_settings/" class="external-link" target="_blank">Pydantic: Settings management</a>.