Tatsächlich gibt es in einigen Fällen sogar **zwei JSON-Schemas** in OpenAPI für dasselbe Pydantic-Modell, für Eingabe und Ausgabe, je nachdem, ob sie **Defaultwerte** haben.

Sehen wir uns an, wie das funktioniert und wie Sie es bei Bedarf ändern können.

## Pydantic-Modelle für Eingabe und Ausgabe { #pydantic-models-for-input-and-output }

Aber wenn Sie mit Ihrem Browser auf <a href="http://127.0.0.1:8000/app" class="external-link" target="_blank">http://127.0.0.1:8000/app</a> gehen, sehen Sie die normale Response:

```JSON
{
    "message": "Hello World",
    "root_path": "/api/v1"
}
```

Es wird also nicht erwartet, dass unter `http://127.0.0.1:8000/api/v1/app` darauf zugegriffen wird.

Sehen wir uns nun an, wie Sie damit eine benutzerdefinierte Response zurückgeben können.

Nehmen wir an, Sie möchten eine <a href="https://en.wikipedia.org/wiki/XML" class="external-link" target="_blank">XML</a>-Response zurückgeben.

// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License

// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License

// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License

// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License

// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License

// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License

# all those branch names and heads as a conservative snapshot
# of the entire remote repo state, and use that as the tag sum.
# Any change on the server then invalidates the tag sum,
# even if it didn't have anything to do with tags, but at least
# we will avoid re-cloning a server when there have been no
# changes at all.
#
# Separately, this extension also adds a 'golookup' command that