## Rendre ce paramètre requis

Quand on ne déclare ni validation, ni métadonnée, on peut rendre le paramètre `q` requis en ne lui déclarant juste aucune valeur par défaut :

```Python
q: str
```

à la place de :

```Python
q: Union[str, None] = None
```

Mais maintenant, on déclare `q` avec `Query`, comme ceci :

```Python
q: Union[str, None] = Query(default=None, min_length=3)
```

    This way, multiple dependencies can have different scopes, even when used in the
    same *path operation*. And with this, you can access all the scopes required in
    all those dependencies in a single place.

    Read more about it in the
    [FastAPI docs for OAuth2 scopes](https://fastapi.tiangolo.com/advanced/security/oauth2-scopes/).
    """

    def __init__(
        self,
        scopes: Annotated[

```

</div>

### Docs Structure

The documentation uses <a href="https://www.mkdocs.org/" class="external-link" target="_blank">MkDocs</a>.

And there are extra tools/scripts in place to handle translations in `./scripts/docs.py`.

!!! tip
    You don't need to see the code in `./scripts/docs.py`, you just use it in the command line.

injection system requires pre-registration of the dependencies and the dependencies are solved based on the declared types. So, it's not possible to declare more than one "component" that provides a certain type.

Routes are declared in a single place, using functions declared in other places (instead of using decorators that can be placed right on top of the function that handles the endpoint). This is closer to how Django does it than to how Flask (and Starlette) does it. It separates in the code...

```Python hl_lines="2"
{!../../../docs_src/python_types/tutorial004.py!}
```

## Declaring types

You just saw the main place to declare type hints. As function parameters.

This is also the main place you would use them with **FastAPI**.

### Simple types

You can declare all the standard Python types, not only `str`.

You can use, for example:

* `int`

À la place, en étant "asynchrone", une fois terminée, une tâche peut légèrement attendre (quelques microsecondes) que l'ordinateur / le programme finisse ce qu'il était en train de faire, et revienne récupérer le résultat.

Nevertheless, there might be cases where we write some code that **crashes the entire application** making Uvicorn and Python crash. 💥

And still, you would probably not want the application to stay dead because there was an error in one place, you probably want it to **continue running** at least for the *path operations* that are not broken.

### Restart After Crash

## What is "Form Data"

The way HTML forms (`<form></form>`) sends the data to the server normally uses a "special" encoding for that data, it's different from JSON.

**FastAPI** will make sure to read that data from the right place instead of JSON.

!!! note "Technical Details"
    Data from forms is normally encoded using the "media type" `application/x-www-form-urlencoded` when it doesn't include files.

know with an error, **Python** will also complain if you run it without passing the required parameter.

When you don't use `Annotated` and instead use the **(old) default value style**, if you call that function without FastAPI in **other place**, you have to **remember** to pass the arguments to the function for it to work correctly, otherwise the values will be different from what you expect (e.g. `QueryInfo` or something similar instead of `str`). And your editor won't complain, and Python...

    assert response.json() == [
        {
            "name": "Breaters",
            "items": [
                {
                    "name": "Island In The Moon",
                    "description": "A place to be be playin' and havin' fun",
                },
                {"name": "Holy Buddies", "description": None},
            ],
        },
        {
            "name": "System of an Up",
            "items": [