///

## Type Hints met Metadata Annotaties

Python heeft ook een functie waarmee je **extra <abbr title="Data over de data, in dit geval informatie over het type, bijvoorbeeld een beschrijving.">metadata</abbr>** in deze type hints kunt toevoegen met behulp van `Annotated`.

//// tab | Python 3.9+

In Python 3.9 is `Annotated` onderdeel van de standaardpakket, dus je kunt het importeren vanuit `typing`.

### Getest

* 100% <abbr title="De hoeveelheid code die automatisch wordt getest">van de code is getest</abbr>.
* 100% <abbr title="Python type annotaties, hiermee kunnen je editor en externe tools je beter ondersteunen">type geannoteerde</abbr> codebase.
* Wordt gebruikt in productietoepassingen.

## Starlette functies

This simple case is handled automatically by FastAPI because the return type annotation is the class (or a subclass of) `Response`.

And tools will also be happy because both `RedirectResponse` and `JSONResponse` are subclasses of `Response`, so the type annotation is correct.

### Annotate a Response Subclass

You can also use a subclass of `Response` in the type annotation:

```Python hl_lines="8-9"

          <option value="io.reactivex.annotations.Beta" />
          <option value="io.reactivex.annotations.Experimental" />
          <option value="org.apache.http.annotation.Beta" />
          <option value="org.gradle.api.Incubating" />
          <option value="org.jetbrains.annotations.ApiStatus.Experimental" />
          <option value="rx.annotations.Beta" />
          <option value="rx.annotations.Experimental" />
        </set>

            default=param.default,
            annotation=get_typed_annotation(param.annotation, globalns),
        )
        for param in signature.parameters.values()
    ]
    typed_signature = inspect.Signature(typed_params)
    return typed_signature


def get_typed_annotation(annotation: Any, globalns: Dict[str, Any]) -> Any:
    if isinstance(annotation, str):
        annotation = ForwardRef(annotation)

7. Here the `response_model` is using a type annotation of a list of `Author` dataclasses.

    Again, you can combine `dataclasses` with standard type annotations.

8. Notice that this *path operation function* uses regular `def` instead of `async def`.

    As always, in FastAPI you can combine `def` and `async def` as needed.

          <item index="3" class="java.lang.String" itemvalue="com.android.annotations.Nullable" />
          <item index="4" class="java.lang.String" itemvalue="edu.umd.cs.findbugs.annotations.Nullable" />
          <item index="5" class="java.lang.String" itemvalue="io.reactivex.annotations.Nullable" />
          <item index="6" class="java.lang.String" itemvalue="io.reactivex.rxjava3.annotations.Nullable" />

            self.deprecated = deprecated
        else:
            kwargs["deprecated"] = deprecated
        if PYDANTIC_V2:
            kwargs.update(
                {
                    "annotation": annotation,
                    "alias_priority": alias_priority,
                    "validation_alias": validation_alias,
                    "serialization_alias": serialization_alias,
                    "strict": strict,

Make sure you [Upgrade the FastAPI version](../deployment/versions.md#upgrading-the-fastapi-versions){.internal-link target=_blank} to at least 0.95.1 before using `Annotated`.

///

## Use `Annotated` in the type for the `q` parameter

```Python
q: Annotated[str | None] = None
```

////

//// tab | Python 3.8+

```Python
q: Annotated[Union[str, None]] = None
```

////

Обе эти версии означают одно и тоже. `q` - это параметр, который может быть `str` или `None`, и по умолчанию он будет принимать `None`.

Давайте повеселимся. 🎉

## Добавим `Query` в `Annotated` для query-параметра `q`