silverstripe-framework/docs/en/02_Developer_Guides/02_Controllers/05_RequestFilters.md

title: Request Filters summary: Create objects for modifying request and response objects across controllers.

Request Filters

[api:RequestFilter] is an interface that provides two key methods. preRequest and postRequest. These methods are executed before and after a request occurs to give developers a hook to modify any global state, add request tracking or perform operations wrapped around responses and request objects. A RequestFilter is defined as:

mysite/code/CustomRequestFilter.php

:::php
<?php

class CustomRequestFilter implements RequestFilter {

	public function preRequest(SS_HTTPRequest $request, Session $session, DataModel $model) {
		
		// if(!something) {
		// 	By returning 'false' from the preRequest method, request execution will be stopped from continuing.
		//	return false;
		// }

		// we can also set any properties onto the request that we need or add any tracking
		// Foo::bar();

		// return true to continue processing.
		return true;
	}

	public function postRequest(SS_HTTPRequest $request, SS_HTTPResponse $response, DataModel $model) {
		// response is about to be sent.
		// any modifications or tracking to be done?
		// Foo::unbar();

		// return true to send the response.
		return true;
	}
}

After defining the RequestFilter, add it as an allowed filter through the Configuration API

mysite/_config/app.yml

:::yml
Injector:
  RequestProcessor:
    properties:
      filters:
        - '%$CustomRequestFilter'

API Documentation

• [api:RequestFilter]
• [api:RequestProcessor]