From a6d2904cb1005ae74faa0a89968760856b32e06c Mon Sep 17 00:00:00 2001
From: Timothy Jacobs <timothyblynjacobs@git.wordpress.org>
Date: Fri, 17 Feb 2023 15:43:47 +0000
Subject: [PATCH] REST API: Normalize WP_REST_Server::dispatch() to return a
 response object.

Previously, the `rest_pre_dispatch` filter could be used to return a `WP_Error` instance. This would cause a fatal error for `rest_post_dispath`
filters that were rightly expecting a `WP_REST_Response` object to be passed instead.

Props DaveFX, felipeelia.
Fixes #56566.


git-svn-id: https://develop.svn.wordpress.org/trunk@55361 602fd350-edb4-49c9-b593-d223f7449a82
---
 .../rest-api/class-wp-rest-server.php         |  9 ++++++
 tests/phpunit/tests/rest-api/rest-server.php  | 32 ++++++++++++++++---
 2 files changed, 37 insertions(+), 4 deletions(-)

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 00c34cd621..4c017eeefa 100644
--- a/src/wp-includes/rest-api/class-wp-rest-server.php
+++ b/src/wp-includes/rest-api/class-wp-rest-server.php
@@ -984,6 +984,15 @@ class WP_REST_Server {
 		$result = apply_filters( 'rest_pre_dispatch', null, $this, $request );
 
 		if ( ! empty( $result ) ) {
+
+			// Normalize to either WP_Error or WP_REST_Response...
+			$result = rest_ensure_response( $result );
+
+			// ...then convert WP_Error across.
+			if ( is_wp_error( $result ) ) {
+				$result = $this->error_to_response( $result );
+			}
+
 			return $result;
 		}
 
diff --git a/tests/phpunit/tests/rest-api/rest-server.php b/tests/phpunit/tests/rest-api/rest-server.php
index 8788a72445..19905cf614 100644
--- a/tests/phpunit/tests/rest-api/rest-server.php
+++ b/tests/phpunit/tests/rest-api/rest-server.php
@@ -922,11 +922,35 @@ class Tests_REST_Server extends WP_Test_REST_TestCase {
 		$data   = array(
 			'untouched' => 'data',
 		);
-		$result = rest_get_server()->embed_links( $data );
+		$result = rest_get_server()->embed_links( $data, true );
 
-		$this->assertArrayNotHasKey( '_links', $data );
-		$this->assertArrayNotHasKey( '_embedded', $data );
-		$this->assertSame( 'data', $data['untouched'] );
+		$this->assertArrayNotHasKey( '_links', $result );
+		$this->assertArrayNotHasKey( '_embedded', $result );
+		$this->assertSame( 'data', $result['untouched'] );
+	}
+
+	/**
+	 * Ensure embed_links handles WP_Error objects returned by dispatch
+	 *
+	 * @ticket 56566
+	 */
+	public function test_link_embedding_returning_wp_error() {
+		$return_wp_error = function() {
+			return new WP_Error( 'some-error', 'This is not valid!' );
+		};
+		add_filter( 'rest_pre_dispatch', $return_wp_error );
+
+		$mock = new MockAction();
+		add_filter( 'rest_post_dispatch', array( $mock, 'filter' ) );
+
+		$response = new WP_REST_Response();
+		$response->add_link( 'author', rest_url( 'test' ), array( 'embeddable' => true ) );
+
+		$data = rest_get_server()->response_to_data( $response, true );
+
+		$this->assertArrayHasKey( '_links', $data );
+		$this->assertCount( 1, $mock->get_events() );
+		$this->assertSame( 'some-error', $data['_embedded']['author'][0]['code'] );
 	}
 
 	public function embedded_response_callback( $request ) {