* **Valider des données** : venant de chaque requête :
    * Générant automatiquement des **erreurs** renvoyées au client quand la donnée est invalide.
* **Documenter** l'API avec OpenAPI :
    * ce qui ensuite utilisé par les interfaces utilisateur automatiques de documentation interactive.

    * `datetime` objects.
    * `UUID` objects.
    * Database models.
    * ...and many more.
* Automatic interactive API documentation, including 2 alternative user interfaces:
    * Swagger UI.
    * ReDoc.

---

Coming back to the previous code example, **FastAPI** will:

* Validate that there is an `item_id` in the path for `GET` and `PUT` requests.

        assertEquals("Second payload should be AnotherTestPayload", AnotherTestPayload.class, multiAnnotation.payload()[1]);
    }

    // Additional test interfaces for multiple groups/payloads test
    private interface AnotherTestGroup {
    }

    private static class AnotherTestPayload implements Payload {
    }

    // Helper methods to get default values

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      "Contribution" shall mean any work of authorship, including
      the original version of the Work and any modifications or additions

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      separable from, or merely link (or bind by name) to the interfaces of,
      the Work and Derivative Works thereof.

      "Contribution" shall mean any work of authorship, including
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whole, an original work of authorship. For the purposes of this License, 
Derivative Works shall not include works that remain separable from, or 
merely link (or bind by name) to the interfaces of, the Work and Derivative 
Works thereof. 

"Contribution" shall mean any work of authorship, including the original 
version of the Work and any modifications or additions to that Work or 

      represent, as a whole, an original work of authorship. For the purposes
      of this License, Derivative Works shall not include works that remain
      separable from, or merely link (or bind by name) to the interfaces of,
      the Work and Derivative Works thereof.

      "Contribution" shall mean any work of authorship, including
      the original version of the Work and any modifications or additions

      represent, as a whole, an original work of authorship. For the purposes
      of this License, Derivative Works shall not include works that remain
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      "Contribution" shall mean any work of authorship, including
      the original version of the Work and any modifications or additions

* Esto también permite el uso de **generación de código cliente automática** en muchos idiomas.

### Documentación automática

Interfaces web de documentación y exploración de APIs interactivas. Como el framework está basado en OpenAPI, hay múltiples opciones, 2 incluidas por defecto.