!!! note "Remarque"
    `JSONResponse` est elle-même une sous-classe de `Response`.

Et quand vous retournez une `Response`, **FastAPI** la transmet directement.

Elle ne fera aucune conversion de données avec les modèles Pydantic, elle ne convertira pas le contenu en un type quelconque.

channel is closed and empty.
</p>


<h3 id="Conversions">Conversions</h3>

<p>
A conversion changes the <a href="#Types">type</a> of an expression
to the type specified by the conversion.
A conversion may appear literally in the source, or it may be <i>implied</i>
by the context in which an expression appears.
</p>

<p>
An <i>explicit</i> conversion is an expression of the form <code>T(x)</code>

 * type</i> of function is expected, use the method reference {@code function::apply}. A future
 * version of {@code com.google.common.base.Function} will be made to <i>extend</i> {@code
 * java.util.function.Function}, making conversion code necessary only in one direction. At that
 * time, this interface will be officially discouraged.
 *
 * @author Kevin Bourrillion
 * @since 2.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault

    que des vérifications d'erreur, de l'auto-complétion, etc.

## <abbr title="aussi appelé sérialisation, ou parfois parsing ou marshalling en anglais">Conversion</abbr> de données

Si vous exécutez cet exemple et allez sur <a href="http://127.0.0.1:8000/items/3" class="external-link" target="_blank">http://127.0.0.1:8000/items/3</a>, vous aurez comme réponse :

```JSON
{"item_id":3}

 * <i>other type</i> of supplier is expected, use the method reference {@code supplier::get}. A
 * future version of {@code com.google.common.base.Supplier} will be made to <i>extend</i> {@code
 * java.util.function.Supplier}, making conversion code necessary only in one direction. At that
 * time, this interface will be officially discouraged.
 *
 * @author Harry Heymann
 * @since 2.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault

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

	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 {

type contentLengthRange struct {
	Min   int64
	Max   int64
	Valid bool // If content-length-range was part of policy
}

// PostPolicyForm provides strict static type conversion and validation for Amazon S3's POST policy JSON string.
type PostPolicyForm struct {
	Expiration time.Time // Expiration date and time of the POST policy.
	Conditions struct {  // Conditional policy structure.

		if helmChartVersion != "" {
			uaAppend(" helm-", helmChartVersion)
		}
		// In Kubernetes environment, try to fetch the Operator, VSPHERE plugin version
		opVersion := env.Get("MINIO_OPERATOR_VERSION", "")
		if opVersion != "" {
			uaAppend(" operator-", opVersion)
		}
		vsphereVersion := env.Get("MINIO_VSPHERE_PLUGIN_VERSION", "")
		if vsphereVersion != "" {
			uaAppend(" vsphere-plugin-", vsphereVersion)
		}
	}

    El `Union` en `Union[str, None]` no es usado por FastAPI (FastAPI solo usará la parte `str`), pero el `Union[str, None]` le permitirá a tu editor ayudarte a encontrar errores en tu código.

## Conversión de tipos de parámetros de query

También puedes declarar tipos `bool` y serán convertidos:

```Python hl_lines="9"
{!../../../docs_src/query_params/tutorial003.py!}
```

En este caso, si vas a:

```

    * <abbr title="en anglais : forms">les formulaires</abbr>.
    * <abbr title="en anglais : files">les fichiers</abbr>.
* <abbr title="aussi connu sous le nom de : serialization, parsing, marshalling">La conversion</abbr> des données de sortie : conversion des données et types Python en données réseau (au format <abbr title="JavaScript Object Notation">JSON</abbr>), permettant de convertir :
    * les types Python (`str`, `int`, `float`, `bool`, `list`, etc).