porter-banner.png...

porter.png...

    ```

In this case, this `__call__` is what **FastAPI** will use to check for additional parameters and sub-dependencies, and this is what will be called to pass a value to the parameter in your *path operation function* later.

## Parameterize the instance

And now, we can use `__init__` to declare the parameters of the instance that we can use to "parameterize" the dependency:

=== "Python 3.9+"

    ```Python hl_lines="9"

        Prefer to use the `Annotated` version if possible.

    ```Python hl_lines="9  14"
    {!> ../../../docs_src/dependencies/tutorial006.py!}
    ```

## Dependencies for a group of *path operations*

    **FastAPI** provides the same `starlette.status` as `fastapi.status` just as a convenience for you, the developer. But it comes directly from Starlette.

## Changing the default

```

with a JSON body of:

```JSON
{
    "id": "2expen51ve",
    "customer": "Mr. Richie Rich",
    "total": "9999"
}
```

then *your API* will process the invoice, and at some point later, send a callback request to the `callback_url` (the *external API*):

```
https://www.external.org/events/invoices/2expen51ve
```

with a JSON body containing something like:

```JSON
{

The `security_scopes` object (of class `SecurityScopes`) also provides a `scope_str` attribute with a single string, containing those scopes separated by spaces (we are going to use it).

We create an `HTTPException` that we can re-use (`raise`) later at several points.

But you can still document it as described in [Additional Responses in OpenAPI](additional-responses.md){.internal-link target=_blank}.

## Main **FastAPI** app

And now in the file `sql_app/main.py` let's integrate and use all the other parts we created before.

### Create the database tables

Der Vorteil, eine Exception auszulösen (`raise`), statt sie zurückzugeben (`return`) wird im Abschnitt über Abhängigkeiten und Sicherheit klarer werden.

Im folgenden Beispiel lösen wir, wenn der Client eine ID anfragt, die nicht existiert, eine Exception mit dem Statuscode `404` aus.

```Python hl_lines="11"
{!../../../docs_src/handling_errors/tutorial001.py!}