# Body - Multiple Parameters { #body-multiple-parameters }

Now that we have seen how to use `Path` and `Query`, let's see more advanced uses of request body declarations.

## Mix `Path`, `Query` and body parameters { #mix-path-query-and-body-parameters }

First, of course, you can mix `Path`, `Query` and request body parameter declarations freely and **FastAPI** will know what to do.

    // for error page

    /**
     * Query string parameter for error page fallback.
     * Contains the original search query if redirection fails.
     */
    public String q;

    /**
     * Number of results parameter for error page fallback.
     * Specifies how many results to display if redirection fails.
     */
    public String num;

    /**
     * Sort parameter for error page fallback.

        // Verify total parameter count (4 bytes at position 3)
        assertEquals(100, SMBUtil.readInt4(dst, 3));

        // Verify total data count (4 bytes at position 7)
        assertEquals(200, SMBUtil.readInt4(dst, 7));

        // Verify parameter count (4 bytes at position 11)
        assertEquals(30, SMBUtil.readInt4(dst, 11));

        // Verify parameter offset (4 bytes at position 15)

* Die Variable `items_s` ist ein `set`, und jedes seiner Elemente ist vom Typ `bytes`.

#### Dict { #dict }

Um ein `dict` zu definieren, übergeben Sie zwei Typ-Parameter, getrennt durch Kommas.

Der erste Typ-Parameter ist für die Schlüssel des `dict`.

Der zweite Typ-Parameter ist für die Werte des `dict`:

{* ../../docs_src/python_types/tutorial008_py39.py hl[1] *}

Das bedeutet:

* Die Variable `prices` ist ein `dict`:

    }

    private Stream<String> getParameterNames(Parameter parameter) {
        if (parameter.getAlias() != null) {
            return Stream.of(parameter.getName(), parameter.getAlias());
        } else {
            return Stream.of(parameter.getName());
        }
    }

    private Set<String> getUnknownParameters(MojoExecution mojoExecution, Set<String> parameters) {

        }
    }

    /**
     * Retrieves an initialization parameter, converting it to the specified class type.
     * @param <T> The type of the parameter.
     * @param key The key of the parameter.
     * @param defaultValue The default value if the parameter is not found.
     * @param clazz The class type to convert the parameter to.
     * @return The parameter value, or the default value if not found.
     */

In this case, the function parameter `q` will be optional, and will be `None` by default.

/// check

Also notice that **FastAPI** is smart enough to notice that the path parameter `item_id` is a path parameter and `q` is not, so, it's a query parameter.

///

## Query parameter type conversion { #query-parameter-type-conversion }

You can also declare `bool` types, and they will be converted:

    /**
     * Returns {@literal true} if the parameter type of the constructor is parameterized.
     *
     * @param index
     *            The index of the parameter
     * @return {@literal true} if the parameter type is parameterized
     */
    boolean isParameterized(int index);

    /**
     * Returns an array of {@link ParameterizedClassDesc} representing the parameter types of the method.
     *

 * types, and also for interfaces and public classes that have public parameter-less constructors.
 * When the non-null default value for a particular parameter type cannot be provided by {@code
 * NullPointerTester}, the caller can provide a custom non-null default value for the parameter type
 * via {@link #setDefault}.
 *
 * @author Kevin Bourrillion
 * @since 10.0
 */
@GwtIncompatible

   * the dummy value of a constructor or method parameter is unknown.
   */
  @VisibleForTesting
  static final class ParameterNotInstantiableException extends Exception {
    public ParameterNotInstantiableException(Parameter parameter) {
      super(
          "Cannot determine value for parameter "
              + parameter
              + " of "
              + parameter.getDeclaringInvokable());
    }
  }