이 경우 함수 매개변수 `q`는 선택적이며 기본값으로 `None` 값이 됩니다.

/// check

또한 **FastAPI**는 `item_id`가 경로 매개변수이고 `q`는 경로 매개변수가 아니라서 쿼리 매개변수라는 것을 알 정도로 충분히 똑똑하다는 점도 확인하세요.

///

## 쿼리 매개변수 형변환 { #query-parameter-type-conversion }

`bool` 형으로 선언할 수도 있고, 아래처럼 변환됩니다:

{* ../../docs_src/query_params/tutorial003_py310.py hl[7] *}

이 경우, 아래로 이동하면:

```
http://127.0.0.1:8000/items/foo?short=1
```

또는

```

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

Cela signifie que **toute valeur** lue en Python à partir d'une variable d'environnement **sera une `str`**, et que toute conversion vers un autre type ou toute validation doit être effectuée dans le code.

Try to be as specific and objective as possible, avoid generalizations.

For conversations that are more difficult, for example to reject a PR, you can ask me (@tiangolo) to handle it directly.

## Edit PR Titles

* Edit the PR title to start with an emoji from [gitmoji](https://gitmoji.dev/).

Prefer to use the `Annotated` version if possible.

///

```Python
commons: CommonQueryParams ...
```

////

...doesn't have any special meaning for **FastAPI**. FastAPI won't use it for data conversion, validation, etc. (as it is using the `Depends(CommonQueryParams)` for that).

You could actually write just:

//// tab | Python 3.10+

```Python
commons: Annotated[Any, Depends(CommonQueryParams)]
```

/// note | Remarque

Notez que, bien que `item` ait été déclaré de la même manière qu'auparavant, il est désormais attendu à l'intérieur du corps de la requête sous la clé `item`.

///

**FastAPI** effectuera la conversion automatique depuis la requête, de sorte que le paramètre `item` reçoive son contenu spécifique, et de même pour `user`.

We could do better.

We can declare a `UserBase` model that serves as a base for our other models. And then we can make subclasses of that model that inherit its attributes (type declarations, validation, etc).

All the data conversion, validation, documentation, etc. will still work as normally.

That way, we can declare just the differences between the models (with plaintext `password`, with `hashed_password` and without password):

Dadurch erhalten Sie Editor-Unterstützung innerhalb Ihrer Funktion, mit Fehlerprüfungen, Codevervollständigung, usw.

///

## Daten-<dfn title="auch bekannt als: Serialisierung, Parsen, Marshalling">Konversion</dfn> { #data-conversion }

Wenn Sie dieses Beispiel ausführen und Ihren Browser unter [http://127.0.0.1:8000/items/3](http://127.0.0.1:8000/items/3) öffnen, sehen Sie als Response:

```JSON
{"item_id":3}
```

/// check | Testen

* <dfn title="también conocido como: serialización, parsing, marshalling">Conversión</dfn> de datos de entrada: de la red a los datos y tipos de Python. Leyendo desde:
    * JSON.
    * Parámetros de path.
    * Parámetros de query.
    * Cookies.
    * Headers.
    * Formularios.
    * Archivos.

         * @return The created query builder.
         */
        QueryBuilder buildQuery(String field, String text, float boost);
    }

    /**
     * Template method that handles the common pattern of query conversion:
     * 1. Check if field is DEFAULT_FIELD and apply default query builder
     * 2. Check if field is a search field and apply field-specific query
     * 3. Fall back to default query builder for unsupported fields
     *