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

Ou bien, en Python 3.10 et supérieur :

```Python
q: str | None = None
```

Par exemple :

//// tab | Python 3.10+

```Python hl_lines="27"
{!> ../../docs_src/body_multiple_params/tutorial004_an_py310.py!}
```

    # o shortCharHandlingMode: (NotRequired - Default NONE)
    #  If the parameter of condition-bean or parameter-bean has short size,
    #   NONE - Do nothing. (default)
    #   EXCEPTION - It throws an exception.
    #   RFILL - It fills the parameter by right spaces.
    #   LFILL - It fills the parameter by left spaces.
    #
    #; shortCharHandlingMode = NONE
    # - - - - - - - - - -/

def lang_callback(lang: Optional[str]) -> Union[str, None]:
    if lang is None:
        return None
    lang = lang.lower()
    return lang


def complete_existing_lang(incomplete: str):
    lang_path: Path
    for lang_path in get_lang_paths():
        if lang_path.is_dir() and lang_path.name.startswith(incomplete):
            yield lang_path.name


@app.callback()
def callback() -> None:
    if is_mkdocs_insiders():

public interface SettingsBuildingRequest {

    /**
     * Gets the global settings file.
     *
     * @return The global settings file or {@code null} if none.
     */
    File getGlobalSettingsFile();

    /**
     * Sets the global settings file. A non-existent settings file is equivalent to empty settings. If both user
     * settings and global settings are given, the user settings take precedence.
     *

    except Exception as e:
        ok = bool(
            await anyio.to_thread.run_sync(
                cm.__exit__, type(e), e, None, limiter=exit_limiter
            )
        )
        if not ok:
            raise e
    else:
        await anyio.to_thread.run_sync(
            cm.__exit__, None, None, None, limiter=exit_limiter

{* ../../docs_src/query_params/tutorial002.py hl[9] *}

Ici, le paramètre `q` sera optionnel, et aura `None` comme valeur par défaut.

/// check | "Remarque"

On peut voir que **FastAPI** est capable de détecter que le paramètre de chemin `item_id` est un paramètre de chemin et que `q` n'en est pas un, c'est donc un paramètre de requête.

///

/// note

                """
            ),
        ],
    ) -> None:
        """
        Move to a position in the file.

        Any next read or write will be done from that position.

        To be awaitable, compatible with async, this is run in threadpool.
        """
        return await super().seek(offset)

    async def close(self) -> None:
        """
        Close the file.

{!> ../../docs_src/body_multiple_params/tutorial001_an.py!}
```

////

//// tab | Python 3.10+ non-Annotated

/// tip

尽可能选择使用 `Annotated` 的版本。

///

```Python hl_lines="17-19"
{!> ../../docs_src/body_multiple_params/tutorial001_py310.py!}
```

////

//// tab | Python 3.8+ non-Annotated

/// tip

尽可能选择使用 `Annotated` 的版本。

///

```Python hl_lines="19-21"

Shubhendu <******@****.***> 1715701387 +0530

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