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!_"

    Es handelt sich also hier um eine Generatorfunktion, die die „generierende“ Arbeit intern auf etwas anderes überträgt.

    Auf diese Weise können wir das Ganze in einen `with`-Block einfügen und so sicherstellen, dass das dateiartige Objekt nach Abschluss geschlossen wird.

### About `**user_in.dict()`

#### Pydantic's `.dict()`

`user_in` is a Pydantic model of class `UserIn`.

Pydantic models have a `.dict()` method that returns a `dict` with the model's data.

So, if we create a Pydantic object `user_in` like:

```Python
user_in = UserIn(username="john", password="secret", email="******@****.***")
```

and then we call:

```Python
user_dict = user_in.dict()
```

So, a request with a content type of `text/plain` containing JSON data would be accepted and the JSON data would be extracted.

When you want to call an `async def` function, you have to "await" it. So, this won't work:

```Python
# This won't work, because get_burgers was defined with: async def
burgers = get_burgers(2)
```

---

The `async` dependency has to be `async` for the context variable to be preserved for the rest of the request, but creating and closing the database connection is potentially blocking, so it could degrade performance if it was there.

We want to get the `current_user` *only* if this user is active.

So, we create an additional dependency `get_current_active_user` that in turn uses `get_current_user` as a dependency.

Both of these dependencies will just return an HTTP error if the user doesn't exist, or if is inactive.

So, in our endpoint, we will only get a user if the user exists, was correctly authenticated, and is active: