From 4c6d7c8498e87ba690764d29da8526b5825c4247 Mon Sep 17 00:00:00 2001
From: Joe Hoyle <joehoyle@git.wordpress.org>
Date: Fri, 30 Sep 2016 20:11:10 +0000
Subject: [PATCH] REST API: Add filters to allow creating REST API middleware
 plugins.

Introduce two new filters: `rest_request_before_callbacks` and `rest_request_after_callbacks` to
assist REST API middleware plugins to perform pre-callback and cleanup hooks such as `switch_to_blog()`
or caching implementations.

Props jnylen0.
Fixes #35590.


git-svn-id: https://develop.svn.wordpress.org/trunk@38689 602fd350-edb4-49c9-b593-d223f7449a82
---
 .../rest-api/class-wp-rest-server.php         | 40 +++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/src/wp-includes/rest-api/class-wp-rest-server.php b/src/wp-includes/rest-api/class-wp-rest-server.php
index 1e5914bfe7..0a763183a9 100644
--- a/src/wp-includes/rest-api/class-wp-rest-server.php
+++ b/src/wp-includes/rest-api/class-wp-rest-server.php
@@ -874,6 +874,24 @@ class WP_REST_Server {
 					}
 				}
 
+				/**
+				 * Call a filter before executing any REST API callbacks.
+				 *
+				 * Allows plugins to perform additional validation after a
+				 * request is initialized and matched to a registered route,
+				 * but before it is executed.
+				 *
+				 * Note that this filter will not be called for requests that
+				 * fail to authenticate or match to a registered route.
+				 *
+				 * @since 4.7.0
+				 *
+				 * @param WP_HTTP_Response $response Result to send to the client. Usually a WP_REST_Response.
+				 * @param WP_REST_Server   $handler  ResponseHandler instance (usually WP_REST_Server).
+				 * @param WP_REST_Request  $request  Request used to generate the response.
+				 */
+				$response = apply_filters( 'rest_request_before_callbacks', $response, $handler, $request );
+
 				if ( ! is_wp_error( $response ) ) {
 					// Check permission specified on the route.
 					if ( ! empty( $handler['permission_callback'] ) ) {
@@ -911,6 +929,28 @@ class WP_REST_Server {
 					}
 				}
 
+				/**
+				 * Call a filter immediately after executing any REST API
+				 * callbacks.
+				 *
+				 * Allows plugins to perform any needed cleanup, for example,
+				 * to undo changes made during `rest_request_before_callbacks`.
+				 *
+				 * Note that this filter will not be called for requests that
+				 * fail to authenticate or match to a registered route.
+				 *
+				 * Note that an endpoint's `permission_callback` can still be
+				 * called after this filter - see the `rest_send_allow_header`
+				 * function.
+				 *
+				 * @since 4.7.0
+				 *
+				 * @param WP_HTTP_Response $response Result to send to the client. Usually a WP_REST_Response.
+				 * @param WP_REST_Server   $handler  ResponseHandler instance (usually WP_REST_Server).
+				 * @param WP_REST_Request  $request  Request used to generate the response.
+				 */
+				$response = apply_filters( 'rest_request_after_callbacks', $response, $handler, $request );
+
 				if ( is_wp_error( $response ) ) {
 					$response = $this->error_to_response( $response );
 				} else {