Aber dieser Leitfaden zeigt Ihnen mehr oder weniger, wie die beiden normalerweise verwendet werden.

///

### Pydantics `exclude_unset`-Parameter verwenden

Wenn Sie Teil-Aktualisierungen entgegennehmen, ist der `exclude_unset`-Parameter in der `.model_dump()`-Methode von Pydantic-Modellen sehr nützlich.

Wie in `item.model_dump(exclude_unset=True)`.

/// info

   *       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

      <version>1.0.0</version>
      <name>ExpressionDocumentation</name>
      <description>The root of a parameter plugin expression document.</description>
      <fields>
        <field>
          <version>1.0.0</version>
          <name>expressions</name>
          <description>The list of plugin parameter expressions described by this
            document.</description>
          <association>

/// tip

Some editors check for unused function parameters, and show them as errors.

Using these `dependencies` in the *path operation decorator* you can make sure they are executed while avoiding editor/tooling errors.

It might also help avoid confusion for new developers that see an unused parameter in your code and could think it's unnecessary.

///

/// info

# 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

        df.setRoundingMode(RoundingMode.HALF_UP);
        return df.format(target) + unit;
    }

    /**
     * Generates URL query parameters for pagination, excluding the specified query parameter.
     *
     * @param query the query parameter to exclude from paging
     * @return URL-encoded query string for pagination
     */
    public static String pagingQuery(final String query) {

* Importieren Sie `HTMLResponse`.
* Übergeben Sie `HTMLResponse` als den Parameter `response_class` Ihres *Pfadoperation-Dekorators*.

{* ../../docs_src/custom_response/tutorial002.py hl[2,7] *}

/// info

Der Parameter `response_class` wird auch verwendet, um den „Medientyp“ der Response zu definieren.

# Response-Header

## Verwenden Sie einen `Response`-Parameter

Sie können einen Parameter vom Typ `Response` in Ihrer *Pfadoperation-Funktion* deklarieren (wie Sie es auch für Cookies tun können).

Und dann können Sie Header in diesem *vorübergehenden* Response-Objekt festlegen.

{* ../../docs_src/response_headers/tutorial002.py hl[1,7:8] *}

Anschließend können Sie wie gewohnt jedes gewünschte Objekt zurückgeben (ein `dict`, ein Datenbankmodell, usw.).

    //                                     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]");
        }
    }

## File Parameters with `UploadFile` { #file-parameters-with-uploadfile }

Define a file parameter with a type of `UploadFile`:

{* ../../docs_src/request_files/tutorial001_an_py39.py hl[14] *}

Using `UploadFile` has several advantages over `bytes`:

* You don't have to use `File()` in the default value of the parameter.
* It uses a "spooled" file: