**FastAPI** wird die automatische Konvertierung des Requests übernehmen, sodass der Parameter `item` seinen spezifischen Inhalt bekommt, genau so wie der Parameter `user`.

Es wird die Validierung dieser zusammengesetzten Daten übernehmen, und sie im OpenAPI-Schema und der automatischen Dokumentation dokumentieren.

## Einzelne Werte im Body

Conversations in the chat systems are also not as easily searchable as in GitHub, so questions and answers might get lost in the conversation. And only the ones in GitHub count to become a [FastAPI Expert](fastapi-people.md#fastapi-experts){.internal-link target=_blank}, so you will most probably receive more attention in GitHub.

Es war eines der ersten extrem schnellen Python-Frameworks, welches auf `asyncio` basierte. Es wurde so gestaltet, dass es Flask sehr ähnlich ist.

!!! note "Technische Details"
    Es verwendete <a href="https://github.com/MagicStack/uvloop" class="external-link" target="_blank">`uvloop`</a> anstelle der standardmäßigen Python-`asyncio`-Schleife. Das hat es so schnell gemacht.

So, what we will do next is add the code to document how that *external API* should look like to receive the callback from *your API*.

**FastAPI** is fully compatible with (and based on) <a href="https://www.starlette.io/" class="external-link" target="_blank"><strong>Starlette</strong></a>. So, any additional Starlette code you have, will also work.

`FastAPI` is actually a sub-class of `Starlette`. So, if you already know or use Starlette, most of the functionality will work the same way.

Python also has a feature that allows putting **additional metadata** in these type hints using `Annotated`.

=== "Python 3.9+"

    In Python 3.9, `Annotated` is part of the standard library, so you can import it from `typing`.

    ```Python hl_lines="1  4"
    {!> ../../../docs_src/python_types/tutorial013_py39.py!}
    ```

=== "Python 3.8+"

## Alternative (old) `Query` as the default value

Previous versions of FastAPI (before <abbr title="before 2023-03">0.95.0</abbr>) required you to use `Query` as the default value of your parameter, instead of putting it in `Annotated`, there's a high chance that you will see code using it around, so I'll explain it to you.

!!! tip

---

"_I’m over the moon excited about **FastAPI**. It’s so fun!_"

---

"_I’m over the moon excited about **FastAPI**. It’s so fun!_"

    ```Python hl_lines="8  13"
    {!> ../../../docs_src/dependencies/tutorial006.py!}
    ```

### Return values

And they can return values or not, the values won't be used.

So, you can re-use a normal dependency (that returns a value) you already use somewhere else, and even though the value won't be used, the dependency will be executed:

=== "Python 3.9+"

    ```Python hl_lines="11  16"