![Swagger UI interaction](https://fastapi.tiangolo.com/img/index/index-04-swagger-03.png)

* Then click on the "Execute" button, the user interface will communicate with your API, send the parameters, get the results and show them on the screen:

![Swagger UI interaction](https://fastapi.tiangolo.com/img/index/index-05-swagger-04.png)

### Alternative API docs upgrade

   b) Accompany the object code with a copy of the GNU GPL and this license
   document.

  4. Combined Works.

  You may convey a Combined Work under terms of your choice that,
taken together, effectively do not restrict modification of the
portions of the Library contained in the Combined Work and reverse
engineering for debugging such modifications, if you also do each of
the following:

Phillip Kravtsov, Pooya Davoodi, Pranav Marathe, Putra Manggala, Qingqing Cao,
Rajeshwar Reddy T, Ramon ViñAs, Rasmus Diederichsen, Reuben Morais, richardbrks,
robert, RonLek, Ryan Jiang, saishruthi, Saket Khandelwal, Saleem Abdulrasool,
Sami Kama, Sana-Damani, Sergii Khomenko, Severen Redwood, Shubham Goyal, Sigrid
Keydana, Siju Samuel, sleighsoft, smilu97, Son Tran, Srini511,

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

!!! tip
    Notice that even though you are accessing it at `http://127.0.0.1:8000/app` it shows the `root_path` of `/api/v1`, taken from the option `--root-path`.

And now open the URL with the port for Traefik, including the path prefix: <a href="http://127.0.0.1:9999/api/v1/app" class="external-link" target="_blank">http://127.0.0.1:9999/api/v1/app</a>.

| `Forwarded`   | For outgoing requests, the original source IP. Note that since we spoof IPs in most cases, this usually is the same as the actual IP seen. For incoming requests, this is used only for traffic from waypoints (which are trusted and cannot spoof IPs) |

    * This allows declaring a parameter like `user_id: str = None` that can be taken from a query parameter, but the same *path operation* can be included in a router with a path `/users/{user_id}`, in which case will be taken from the path and will be required.
    * PR [#464](https://github.com/tiangolo/fastapi/pull/464) by [@jonathanunderwood](https://github.com/jonathanunderwood).

![Swagger UI interaction](https://fastapi.tiangolo.com/img/index/index-04-swagger-03.png)

* Then click on the "Execute" button, the user interface will communicate with your API, send the parameters, get the results and show them on the screen:

![Swagger UI interaction](https://fastapi.tiangolo.com/img/index/index-05-swagger-04.png)

### Alternative API docs upgrade