* parameters.
   */
  public MediaType withoutParameters() {
    return parameters.isEmpty() ? this : create(type, subtype);
  }

  /**
   * Replaces all parameters with the given parameters.
   *
   * @throws IllegalArgumentException if any parameter or value is invalid
   */

# Cookie Parameter Models { #cookie-parameter-models }

If you have a group of **cookies** that are related, you can create a **Pydantic model** to declare them. 🍪

This would allow you to **re-use the model** in **multiple places** and also to declare validations and metadata for all the parameters at once. 😎

/// note

This is supported since FastAPI version `0.115.0`. 🤓

///

/// tip

# Response Headers { #response-headers }

## Use a `Response` parameter { #use-a-response-parameter }

You can declare a parameter of type `Response` in your *path operation function* (as you can do for cookies).

And then you can set headers in that *temporal* response object.

{* ../../docs_src/response_headers/tutorial002_py39.py hl[1, 7:8] *}

And then you can return any object you need, as you normally would (a `dict`, a database model, etc).

                "Field nonFinalField: Nullability breaking change.",
                "Method com.example.Source.foo(java.lang.String[]): Parameter 0 from null accepting to non-null accepting breaking change.",
                "Constructor com.example.Source(java.lang.String[]): Parameter 0 from null accepting to non-null accepting breaking change."
            )
            assertHasNoWarning()
            assertHasNoInformation()

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.

{* ../../docs_src/security/tutorial001_an_py39.py hl[8] *}

    /**
     * Sets the initialization parameter map for this wrapper.
     * These parameters will be applied to the wrapped factory upon calling initParameterMap().
     * @param params The map of parameters.
     */
    @Override
    public void setInitParameterMap(final Map<String, Object> params) {
        this.params.putAll(params);
    }

    /**

    //                                     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]");
        }
    }

        } ?: return // Expected a value.

      val replaced = parameters.put(peek, parameterValue)
      peek = null
      if (replaced != null) return // Unexpected duplicate parameter.
      if (!skipCommasAndWhitespace() && !exhausted()) return // Expected ',' or EOF.
    }
    result.add(Challenge(schemeName, parameters))
  }
}

/** Returns true if any commas were skipped. */

## Using `BackgroundTasks` { #using-backgroundtasks }

First, import `BackgroundTasks` and define a parameter in your *path operation function* with a type declaration of `BackgroundTasks`:

{* ../../docs_src/background_tasks/tutorial001_py39.py hl[1,13] *}

**FastAPI** will create the object of type `BackgroundTasks` for you and pass it as that parameter.

## Create a task function { #create-a-task-function }

* der Requestbody
* der Responsebody
* der JSON-Body
* der Formularbody
* der Dateibody
* der Funktionskörper

* der Parameter
* der Body-Parameter
* der Pfad-Parameter
* der Query-Parameter
* der Cookie-Parameter
* der Header-Parameter
* der Formular-Parameter
* der Funktionsparameter

* das Event
* das Startup-Event
* das Hochfahren des Servers
* das Shutdown-Event