{!> ../../docs_src/dependencies/tutorial005.py!}
```

////

Let's focus on the parameters declared:

* Even though this function is a dependency ("dependable") itself, it also declares another dependency (it "depends" on something else).
    * It depends on the `query_extractor`, and assigns the value returned by it to the parameter `q`.
* It also declares an optional `last_query` cookie, as a `str`.

As an example, let's take this function:

{* ../../docs_src/python_types/tutorial009c.py hl[1,4] *}

The parameter `name` is defined as `Optional[str]`, but it is **not optional**, you cannot call the function without the parameter:

```Python
say_hi()  # Oh, no, this throws an error! 😱
```

The `name` parameter is **still required** (not *optional*) because it doesn't have a default value. Still, `name` accepts `None` as the value:

/// info

`Form` ist eine Klasse, die direkt von `Body` erbt.

///

/// tip | "Tipp"

Um Formularbodys zu deklarieren, verwenden Sie explizit `Form`, da diese Parameter sonst als Query-Parameter oder Body(-JSON)-Parameter interpretiert werden würden.

///

## Über „Formularfelder“

HTML-Formulare (`<form></form>`) senden die Daten in einer „speziellen“ Kodierung zum Server, welche sich von JSON unterscheidet.

```Python hl_lines="17  22  24-27"
{!> ../../docs_src/response_model/tutorial001.py!}
```

////

/// note | "Hinweis"

Beachten Sie, dass `response_model` ein Parameter der „Dekorator“-Methode ist (`get`, `post`, usw.). Nicht der *Pfadoperation-Funktion*, so wie die anderen Parameter.

///

    //                                     Parameter Logging
    //                                     -----------------
    // logging filter cannot show the parameters when multi-part so logging here
    protected void showFieldLoggingTitle() {
        if (logger.isDebugEnabled()) {
            logger.debug("[Multipart Request Parameter]");
        }
    }

In that case, **FastAPI** also provides you with the tools to build it.

///

When we create an instance of the `OAuth2PasswordBearer` class we pass in the `tokenUrl` parameter. This parameter contains the URL that the client (the frontend running in the user's browser) will use to send the `username` and `password` in order to get a token.

//// tab | Python 3.9+

```Python hl_lines="8"

 * <td colspan="3">
 * <b>Examples Of SMB URLs When Augmented With A Second Constructor Parameter</b></td>
 * <tr><td width="20%">
 * <b>First Parameter</b></td><td><b>Second Parameter</b></td><td><b>Result</b></td></tr>
 *
 * <tr><td width="20%"><code>
 *  smb1://host/share/a/b/
 * </code></td><td width="20%"><code>
 *  c/d/
 * </code></td><td><code>
 *  smb1://host/share/a/b/c/d/
 * </code></td></tr>
 * 

## Zusätzliche Response mit `model`

Sie können Ihren *Pfadoperation-Dekoratoren* einen Parameter `responses` übergeben.

Der nimmt ein `dict` entgegen, die Schlüssel sind Statuscodes für jede Response, wie etwa `200`, und die Werte sind andere `dict`s mit den Informationen für jede Response.

E.g.:

* To pass a *path* or *query* parameter, add it to the URL itself.
* To pass a JSON body, pass a Python object (e.g. a `dict`) to the parameter `json`.
* If you need to send *Form Data* instead of JSON, use the `data` parameter instead.
* To pass *headers*, use a `dict` in the `headers` parameter.
* For *cookies*, a `dict` in the `cookies` parameter.

   *       to construct the sample instances. In case of tie, the candidate constructors or
   *       factories are tried one after another until one can be used to construct sample
   *       instances.
   *   <li>For the constructor or static factory method used to construct instances, it's checked