# Custom Request and APIRoute class { #custom-request-and-apiroute-class }

In some cases, you may want to override the logic used by the `Request` and `APIRoute` classes.

In particular, this may be a good alternative to logic in a middleware.

For example, if you want to read or manipulate the request body before it is processed by your application.

/// danger

This is an "advanced" feature.

If you want to use your APIs' function names as `operationId`s, you can iterate over all of them and override each *path operation's* `operation_id` using their `APIRoute.name`.

You should do it after adding all your *path operations*.

{* ../../docs_src/path_operation_advanced_configuration/tutorial002.py hl[2, 12:21, 24] *}

/// tip

FastAPI uses a **unique ID** for each *path operation*, which is used for the **operation ID** and also for the names of any needed custom models, for requests or responses.

You can customize that function. It takes an `APIRoute` and outputs a string.

For example, here it is using the first tag (you will probably have only one tag) and the *path operation* name (the function name).

    * If you have advanced custom logic to access each route's `route.response_class`, or the `router.default_response_class`, or the `app.default_response_class`: the default value for `response_class` in `APIRoute` and for `default_response_class` in `APIRouter` and `FastAPI` is now a `DefaultPlaceholder` used internally to handle and solve default values and overrides. The actual response class inside the `DefaultPlaceholder` is available at `route.response_class.value`....