From 30ff995eb0aa2660ef4b08b9e3c5f7b0126c702b Mon Sep 17 00:00:00 2001
From: Sergey Biryukov <sergeybiryukov@git.wordpress.org>
Date: Tue, 27 Apr 2021 18:34:52 +0000
Subject: [PATCH] REST API: Check the results of `get_metadata()` in
 `WP_REST_Meta_Fields` methods.

This avoids PHP warnings in case the function returns boolean `false` instead of an array.

Props david.binda.
Fixes #53099.

git-svn-id: https://develop.svn.wordpress.org/trunk@50793 602fd350-edb4-49c9-b593-d223f7449a82
---
 .../fields/class-wp-rest-meta-fields.php      | 14 ++++--
 .../tests/rest-api/rest-term-meta-fields.php  | 48 +++++++++++++++++++
 2 files changed, 59 insertions(+), 3 deletions(-)

diff --git a/src/wp-includes/rest-api/fields/class-wp-rest-meta-fields.php b/src/wp-includes/rest-api/fields/class-wp-rest-meta-fields.php
index 817f5c106a..f186648545 100644
--- a/src/wp-includes/rest-api/fields/class-wp-rest-meta-fields.php
+++ b/src/wp-includes/rest-api/fields/class-wp-rest-meta-fields.php
@@ -94,8 +94,10 @@ abstract class WP_REST_Meta_Fields {
 			} else {
 				$value = array();
 
-				foreach ( $all_values as $row ) {
-					$value[] = $this->prepare_value_for_response( $row, $request, $args );
+				if ( is_array( $all_values ) ) {
+					foreach ( $all_values as $row ) {
+						$value[] = $this->prepare_value_for_response( $row, $request, $args );
+					}
 				}
 			}
 
@@ -281,6 +283,10 @@ abstract class WP_REST_Meta_Fields {
 		$current_values = get_metadata( $meta_type, $object_id, $meta_key, false );
 		$subtype        = get_object_subtype( $meta_type, $object_id );
 
+		if ( ! is_array( $current_values ) ) {
+			$current_values = array();
+		}
+
 		$to_remove = $current_values;
 		$to_add    = $values;
 
@@ -377,7 +383,9 @@ abstract class WP_REST_Meta_Fields {
 		$old_value = get_metadata( $meta_type, $object_id, $meta_key );
 		$subtype   = get_object_subtype( $meta_type, $object_id );
 
-		if ( 1 === count( $old_value ) && $this->is_meta_value_same_as_stored_value( $meta_key, $subtype, $old_value[0], $value ) ) {
+		if ( is_array( $old_value ) && 1 === count( $old_value )
+			&& $this->is_meta_value_same_as_stored_value( $meta_key, $subtype, $old_value[0], $value )
+		) {
 			return true;
 		}
 
diff --git a/tests/phpunit/tests/rest-api/rest-term-meta-fields.php b/tests/phpunit/tests/rest-api/rest-term-meta-fields.php
index 6c8f3a0135..8ed2a0a26f 100644
--- a/tests/phpunit/tests/rest-api/rest-term-meta-fields.php
+++ b/tests/phpunit/tests/rest-api/rest-term-meta-fields.php
@@ -1285,6 +1285,54 @@ class WP_Test_REST_Term_Meta_Fields extends WP_Test_REST_TestCase {
 		$this->assertSame( 'Goodbye', $meta[ $meta_key ] );
 	}
 
+	/**
+	 * @ticket 53099
+	 */
+	public function test_get_term_metadata_returning_false_does_not_cause_php_warnings() {
+		add_filter( 'get_term_metadata', '__return_false', 11 );
+
+		// No PHP warning during GET request.
+		add_term_meta( self::$category_id, 'test_single', 'testvalue' );
+		$request  = new WP_REST_Request( 'GET', sprintf( '/wp/v2/categories/%d', self::$category_id ) );
+		$response = rest_get_server()->dispatch( $request );
+
+		// No PHP warning during POST request.
+		$this->grant_write_permission();
+		$data    = array(
+			'meta' => array(
+				'test_multi' => array( 'val1' ),
+			),
+		);
+		$request = new WP_REST_Request( 'POST', sprintf( '/wp/v2/categories/%d', self::$category_id ) );
+		$request->set_body_params( $data );
+		$response = rest_get_server()->dispatch( $request );
+
+		// No PHP warning during validation.
+		register_meta(
+			'term',
+			'my_meta_key',
+			array(
+				'show_in_rest' => true,
+				'single'       => true,
+				'type'         => 'integer',
+			)
+		);
+		$this->grant_write_permission();
+		$data    = array(
+			'meta' => array(
+				'my_meta_key' => '1', // Set to a string.
+			),
+		);
+		$request = new WP_REST_Request( 'POST', sprintf( '/wp/v2/categories/%d', self::$category_id ) );
+		$request->set_body_params( $data );
+		$response = rest_get_server()->dispatch( $request );
+
+		remove_filter( 'get_term_metadata', '__return_false', 11 );
+
+		$data = $response->get_data();
+		$this->assertSame( 0, $data['meta']['my_meta_key'] );
+	}
+
 	/**
 	 * Internal function used to disable an insert query which
 	 * will trigger a wpdb error for testing purposes.