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

```

                assertNotNull(upgrade.artifactId(), "Plugin upgrade should have artifactId");
                assertNotNull(upgrade.minVersion(), "Plugin upgrade should have minVersion");
                // configuration can be null for some plugins
            }
        }
    }

    @Nested
    @DisplayName("Error Handling")
    class ErrorHandlingTests {

			if err != nil {
				return nil, err
			}
		}

		client, err := kms.NewClient(&kms.Config{
			Endpoints: endpoints,
			APIKey:    key,
			TLS: &tls.Config{
				MinVersion:         tls.VersionTLS12,
				ClientSessionCache: tls.NewLRUClientSessionCache(tlsClientSessionCacheSize),
				RootCAs:            rootCAs,
			},
		})
		if err != nil {
			return nil, err
		}

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.

		err = errors.New("entity too large")
		return partSize, err
	}

	configuredPartSize := minPartSize
	// Use floats for part size for all calculations to avoid
	// overflows during float64 to int64 conversions.
	partSizeFlt := float64(objectSize / maxPartsCount)
	partSizeFlt = math.Ceil(partSizeFlt/float64(configuredPartSize)) * float64(configuredPartSize)

	// Part size.
	partSize = int64(partSizeFlt)
	if partSize == 0 {

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)]
```

   * java.util.Optional}, or {@code null} if the argument is null.
   *
   * @since 21.0 (but only since 33.4.0 in the Android flavor)
   */
  @SuppressWarnings("NullableOptional") // Null passthrough is reasonable for type conversions
  public static <T> @Nullable Optional<T> fromJavaUtil(
      java.util.@Nullable Optional<T> javaUtilOptional) {
    return (javaUtilOptional == null) ? null : fromNullable(javaUtilOptional.orElse(null));
  }

/// 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):