Actually, all (or most) of the web frameworks work in this same way.

You never call those functions directly. They are called by your framework (in this case, **FastAPI**).

* Data validation
* API annotation and automatic documentation

And you only have to declare them once.

---

FastAPI is a modern, fast (high-performance), web framework for building APIs with Python based on standard Python type hints.

The key features are:

* **Fast**: Very high performance, on par with **NodeJS** and **Go** (thanks to Starlette and Pydantic). [One of the fastest Python frameworks available](#performance).
* **Fast to code**: Increase the speed to develop features by about 200% to 300%. *

 *
 * <p>To decouple components, we recommend a dependency-injection framework. For Android code, most
 * apps use <a href="https://dagger.dev">Dagger</a>. For server code, common options include <a
 * href="https://github.com/google/guice/wiki/Motivation">Guice</a> and <a
 * href="https://docs.spring.io/spring-framework/docs/current/reference/html/core.html#beans-introduction">Spring</a>.

         * a clear specification for what annotations should mean on resolved TypeVariables
         * with modified bounds, annotation methods will throw
         * UnsupportedOperationException. Frameworks requiring annotation preservation
         * should use the original TypeVariable when bounds haven't changed.
         */
        if (Types.NativeTypeVariableEquals.NATIVE_TYPE_VARIABLE_ONLY

 * Futures#transform(ListenableFuture, Function, Executor) Futures.transform}, but you will often
 * find it easier to use a framework. Frameworks automate the process, often adding features like
 * monitoring, debugging, and cancellation. Examples of frameworks include:
 *
 * <ul>
 *   <li><a href="https://dagger.dev/producers.html">Dagger Producers</a>
 * </ul>
 *

    * Si on compare FastAPI, il faut le comparer à d'autres frameworks d’application web (ou ensembles d'outils) qui fournissent la validation des données, la sérialisation et la documentation, comme Flask-apispec, NestJS, Molten, etc. Des frameworks avec validation des données, sérialisation et documentation automatiques intégrées....

    * Si estás comparando FastAPI, compáralo con un framework de aplicación web (o conjunto de herramientas) que proporcione validación de datos, serialización y documentación, como Flask-apispec, NestJS, Molten, etc. Frameworks con validación de datos, serialización y documentación automáticas integradas....

### [Django REST Framework](https://www.django-rest-framework.org/) { #django-rest-framework }

Django REST Framework a été conçu comme une boîte à outils flexible permettant de construire des API Web à partir de Django, afin d'améliorer ses capacités en matière d'API.

    * Wenn Sie FastAPI vergleichen, vergleichen Sie es mit einem Webanwendungs-Framework (oder einer Reihe von Tools), das Datenvalidierung, Serialisierung und Dokumentation bereitstellt, wie Flask-apispec, NestJS, Molten, usw. – Frameworks mit integrierter automatischer Datenvalidierung, Serialisierung und Dokumentation....