# Utiliser des dataclasses { #using-dataclasses }

FastAPI est construit au‑dessus de **Pydantic**, et je vous ai montré comment utiliser des modèles Pydantic pour déclarer les requêtes et les réponses.

Mais FastAPI prend aussi en charge l'utilisation de [`dataclasses`](https://docs.python.org/3/library/dataclasses.html) de la même manière :

{* ../../docs_src/dataclasses_/tutorial001_py310.py hl[1,6:11,18:19] *}

{* ../../docs_src/server_sent_events/tutorial001_py310.py ln[34:37] hl[35] *}

## `ServerSentEvent` { #serversentevent }

Se você precisar definir campos de SSE como `event`, `id`, `retry` ou `comment`, você pode produzir objetos `ServerSentEvent` em vez de dados simples.

Importe `ServerSentEvent` de `fastapi.sse`:

{* ../../docs_src/server_sent_events/tutorial002_py310.py hl[4,26] *}

MINIO_POLICY_PLUGIN_ENABLE_HTTP2  (bool)      Enable experimental HTTP2 support to connect to plugin service (default: 'off')
MINIO_POLICY_PLUGIN_COMMENT       (sentence)  optionally add a comment to this setting
```

By default this plugin uses HTTP 1.x. To enable HTTP2 use the `MINIO_POLICY_PLUGIN_ENABLE_HTTP2` environment variable.

## Request and Response

			Optional:    true,
			Type:        "string",
		},
		config.HelpKV{
			Key:         config.Comment,
			Description: config.DefaultComment,
			Optional:    true,
			Type:        "sentence",
		},
	}

import java.util.HashMap;
import java.util.Map;

import org.codelibs.fess.opensearch.user.allcommon.EsAbstractEntity;
import org.codelibs.fess.opensearch.user.bsentity.dbmeta.UserDbm;

/**
 * ${table.comment}
 * @author ESFlute (using FreeGen)
 */
public class BsUser extends EsAbstractEntity {

    // ===================================================================================

```

com um corpo JSON de:

```JSON
{
    "id": "2expen51ve",
    "customer": "Mr. Richie Rich",
    "total": "9999"
}
```

então *sua API* processará a fatura e, em algum momento posterior, enviará um request de callback para o `callback_url` (a *API externa*):

```
https://www.external.org/events/invoices/2expen51ve
```

com um corpo JSON contendo algo como:

```JSON
{

# o isSuppressDropProcedure: (NotRequired - Default false)
# o isSuppressDropDBLink: (NotRequired - Default false)
# o initializeFirstSqlList: (NotRequired - Default list:{})
#
# *The line that starts with '#' means comment-out.
#
map:{
    # /- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    # o repsEnvType: (NotRequired - Default inherits or 'ut')
    #  The environment type of ReplaceSchema.

**FastAPI** sait quoi faire dans chaque cas et comment réutiliser le même objet, afin que toutes les tâches d'arrière-plan soient fusionnées et que les tâches soient ensuite exécutées en arrière-plan :

{* ../../docs_src/background_tasks/tutorial002_an_py310.py hl[13,15,22,25] *}

     */
    private void writeCoreExtensions(CoreExtensions coreExtensions, String tagName, XmlSerializer serializer)
            throws IOException {
        if (this.fileComment != null) {
            serializer.comment(this.fileComment);
        }
        serializer.setPrefix("", "http://maven.apache.org/EXTENSIONS/1.1.0");
        serializer.setPrefix("xsi", "http://www.w3.org/2001/XMLSchema-instance");

{* ../../docs_src/server_sent_events/tutorial001_py310.py ln[34:37] hl[35] *}

## `ServerSentEvent` { #serversentevent }

`event`, `id`, `retry` veya `comment` gibi SSE alanlarını ayarlamanız gerekirse, düz veri yerine `ServerSentEvent` nesneleri yield edebilirsiniz.

`ServerSentEvent`'i `fastapi.sse` içinden içe aktarın: