That information will be included in the generated OpenAPI and used by the documentation user interfaces and external tools.

!!! note
    Keep in mind that different tools might have different levels of OpenAPI support.

    Some of them might not show all the extra information declared yet, although in most of the cases, the missing feature is already planned for development.

You can add a `title`:

=== "Python 3.10+"

This can make it a lot easier for your users to **implement their APIs** to receive your **webhook** requests, they might even be able to autogenerate some of their own API code.

!!! info
    Webhooks are available in OpenAPI 3.1.0 and above, supported by FastAPI `0.99.0` and above.

## An app with webhooks

title: Build The Next Generation Of Python Web Applications With FastAPI - Episode 259 - interview to Sebastían Ramírez (tiangolo) - author: Python Bytes FM author_link: https://pythonbytes.fm/ link: https://pythonbytes.fm/episodes/show/123/time-to-right-the-py-wrongs?time_in_sec=855 title: FastAPI on PythonBytes Talks: English: - author: Jeny Sadadia author_link: https://github.com/JenySadadia link: https://www.youtube.com/watch?v=uZdTe8_Z6BQ title: 'PyCon AU 2023: Testing asynchronous applications...

                    "description": "The kombucha mushroom people's favorite",
                },
                {"name": "Pad Thai", "description": None},
                {
                    "name": "Lonely Night",
                    "description": "The mostests lonliest nightiest of allest",
                },
            ],
        },
    ]


@needs_pydanticv2
def test_openapi_schema():

It uses the information from Webargs and Marshmallow to automatically generate OpenAPI schemas, using APISpec.

It's a great tool, very underrated. It should be way more popular than many Flask plug-ins out there. It might be due to its documentation being too concise and abstract.

This solved having to write YAML (another syntax) inside of Python docstrings.

For example, if you want to read or manipulate the request body before it is processed by your application.

!!! danger
    This is an "advanced" feature.

    If you are just starting with **FastAPI** you might want to skip this section.

## Use cases

Some use cases include:

* Converting non-JSON request bodies to JSON (e.g. <a href="https://msgpack.org/index.html" class="external-link" target="_blank">`msgpack`</a>).

This could be useful, for example, to expose the same API under different prefixes, e.g. `/api/v1` and `/api/latest`.

This is an advanced usage that you might not really need, but it's there in case you do.

## Include an `APIRouter` in another

The same way you can include an `APIRouter` in a `FastAPI` application, you can include an `APIRouter` in another `APIRouter` using:

## Separating tests

In a real application, you probably would have your tests in a different file.

And your **FastAPI** application might also be composed of several files/modules, etc.

### **FastAPI** app file

Let's say you have a file structure as described in [Bigger Applications](bigger-applications.md){.internal-link target=_blank}:

```
.

```
.
├── app
│   ├── __init__.py
│   ├── main.py
└── static/
```

### Download the files

Download the static files needed for the docs and put them on that `static/` directory.

You can probably right-click each link and select an option similar to `Save link as...`.

**Swagger UI** uses the files:

!!! tip
    When writing the code to document a callback, it might be useful to imagine that you are that *external developer*. And that you are currently implementing the *external API*, not *your API*.