This will (let's imagine) let the API user (some external developer) create an
    invoice.

    And this path operation will:

    * Send the invoice to the client.
    * Collect the money from the client.
    * Send a notification back to the API user (the external developer), as a callback.
        * At this point is that the API will somehow send a POST request to the
            external API with the notification of the invoice event

* <a href="https://github.com/swagger-api/swagger-ui" class="external-link" target="_blank"><strong>Swagger UI</strong></a>, с интерактивным взаимодействием, вызывает и тестирует ваш API прямо из браузера.

![Swagger UI interaction](https://fastapi.tiangolo.com/img/index/index-03-swagger-02.png)

* Альтернативная документация API в <a href="https://github.com/Rebilly/ReDoc" class="external-link" target="_blank"><strong>ReDoc</strong></a>.

* <a href="https://stackshare.io/pypi-fastapi" class="external-link" target="_blank">Расскажите, как Вы используете **FastAPI** на StackShare</a>.

## Помочь другим с их проблемами на GitHub

The process that happens when your API app calls the *external API* is named a "callback". Because the software that the external developer wrote sends a request to your API and then your API *calls back*, sending a request to an *external API* (that was probably created by the same developer).

## Quraşdırma

<div class="termy">

```console
$ pip install fastapi

---> 100%
```

</div>

Tətbiqimizi əlçatan etmək üçün bizə <a href="https://www.uvicorn.org" class="external-link" target="_blank">Uvicorn</a> və ya <a href="https://github.com/pgjones/hypercorn" class="external-link" target="_blank">Hypercorn</a> kimi ASGI server lazımdır.

    This will (let's imagine) let the API user (some external developer) create an
    invoice.

    And this path operation will:

    * Send the invoice to the client.
    * Collect the money from the client.
    * Send a notification back to the API user (the external developer), as a callback.
        * At this point is that the API will somehow send a POST request to the
            external API with the notification of the invoice event

### Проверьте

Откройте браузер по адресу: <a href="http://127.0.0.1:8000" class="external-link" target="_blank">http://127.0.0.1:8000</a>.

Вы увидите JSON-ответ следующего вида:

```JSON
{"message": "Hello World"}
```

### Интерактивная документация API

Перейдите по адресу: <a href="http://127.0.0.1:8000/docs" class="external-link" target="_blank">http://127.0.0.1:8000/docs</a>.

Vous verrez la documentation interactive automatique de l'API (fournie par <a href="https://github.com/swagger-api/swagger-ui" class="external-link" target="_blank">Swagger UI</a>) :

Because of this, **FastAPI** itself provides an alternative API documentation (using ReDoc), which you can access at <a href="http://127.0.0.1:8000/redoc" class="external-link" target="_blank">http://127.0.0.1:8000/redoc</a>:

<img src="/img/tutorial/path-params/image02.png">

Es por esto que **FastAPI** mismo provee una documentación alternativa de la API (usando ReDoc), a la que puedes acceder en <a href="http://127.0.0.1:8000/redoc" class="external-link" target="_blank">http://127.0.0.1:8000/redoc</a>:

<img src="/img/tutorial/path-params/image02.png">