router_sig = inspect.signature(router_method)
        app_sig = inspect.signature(app_method)
        param: inspect.Parameter
        for key, param in base_sig.parameters.items():
            router_param: inspect.Parameter = router_sig.parameters[key]
            app_param: inspect.Parameter = app_sig.parameters[key]
            assert param.annotation == router_param.annotation
            assert param.annotation == app_param.annotation

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:

# Path Parameters { #path-parameters }

You can declare path "parameters" or "variables" with the same syntax used by Python format strings:

{* ../../docs_src/path_params/tutorial001_py310.py hl[6:7] *}

The value of the path parameter `item_id` will be passed to your function as the argument `item_id`.

So, if you run this example and go to [http://127.0.0.1:8000/items/foo](http://127.0.0.1:8000/items/foo), you will see a response of:

```JSON

                    logger.warn("Failed to store search parameters in cookie.", e);
                }
            }
        });
    }

    /**
     * Serializes request parameters to a compressed and encoded string.
     *
     * @param parameters Array of request parameters to serialize
     * @return Base64-encoded, GZIP-compressed JSON string of parameters
     * @throws SearchQueryException if serialization fails

    }
  }

  /*
   * Preconditions.checkNotNull is *intended* for performing eager null checks on parameters that a
   * nullness checker can already "prove" are non-null. That means that the first parameter to
   * checkNotNull *should* be annotated to require it to be non-null.
   *
   * However, for a variety of reasons, Google developers have written a ton of code over the past

# Paramètres d'en-tête { #header-parameters }

Vous pouvez définir des paramètres `Header` de la même manière que vous définissez des paramètres `Query`, `Path` et `Cookie`.

## Importer `Header` { #import-header }

Commencez par importer `Header` :

{* ../../docs_src/header_params/tutorial001_an_py310.py hl[3] *}

## Déclarer des paramètres `Header` { #declare-header-parameters }

# Header Parameters { #header-parameters }

You can define Header parameters the same way you define `Query`, `Path` and `Cookie` parameters.

## Import `Header` { #import-header }

First import `Header`:

{* ../../docs_src/header_params/tutorial001_an_py310.py hl[3] *}

## Declare `Header` parameters { #declare-header-parameters }

Then declare the header parameters using the same structure as with `Path`, `Query` and `Cookie`.

        }
    }

    /**
     * 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.
     */

{* ../../docs_src/dependencies/tutorial001_an_py310.py hl[13,18] *}

Although you use `Depends` in the parameters of your function the same way you use `Body`, `Query`, etc, `Depends` works a bit differently.

You only give `Depends` a single parameter.

This parameter must be something like a function.

Par exemple, pour désactiver `deepLinking`, vous pourriez passer ces paramètres à `swagger_ui_parameters` :

{* ../../docs_src/configure_swagger_ui/tutorial003_py310.py hl[3] *}

## Autres paramètres de Swagger UI { #other-swagger-ui-parameters }