REST API: Fix updating "multiple" meta keys with non-string values.

Previously, the REST API would end up deleting each row of metadata and recreating it unnecessarily. This was caused by a type mismatch where the metadata API would always return a string value, and the REST API operated on a typed value.

The REST API now applies the same sanitization and type casting for "multiple" meta keys and "single" meta keys.

Fixes #49339.
Props renathoc.

Built from https://develop.svn.wordpress.org/trunk@47943


git-svn-id: http://core.svn.wordpress.org/trunk@47716 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/rest-api/fields/class-wp-rest-meta-fields.php

@@ -269,13 +269,21 @@ abstract class WP_REST_Meta_Fields {
 			);
 		}
 
-		$current = get_metadata( $meta_type, $object_id, $meta_key, false );
+		$current_values = get_metadata( $meta_type, $object_id, $meta_key, false );
+		$subtype        = get_object_subtype( $meta_type, $object_id );
 
-		$to_remove = $current;
+		$to_remove = $current_values;
 		$to_add    = $values;
 
 		foreach ( $to_add as $add_key => $value ) {
-			$remove_keys = array_keys( $to_remove, $value, true );
+			$remove_keys = array_keys(
+				array_filter(
+					$current_values,
+					function ( $stored_value ) use ( $meta_key, $subtype, $value ) {
+						return $this->is_meta_value_same_as_stored_value( $meta_key, $subtype, $stored_value, $value );
+					}
+				)
+			);
 
 			if ( empty( $remove_keys ) ) {
 				continue;
@@ -359,20 +367,10 @@ abstract class WP_REST_Meta_Fields {
 		// Do the exact same check for a duplicate value as in update_metadata() to avoid update_metadata() returning false.
 		$old_value = get_metadata( $meta_type, $object_id, $meta_key );
 		$subtype   = get_object_subtype( $meta_type, $object_id );
-		$args      = $this->get_registered_fields()[ $meta_key ];
 
-		if ( 1 === count( $old_value ) ) {
+		if ( 1 === count( $old_value ) && $this->is_meta_value_same_as_stored_value( $meta_key, $subtype, $old_value[0], $value ) ) {
-			$sanitized = sanitize_meta( $meta_key, $value, $meta_type, $subtype );
-
-			if ( in_array( $args['type'], array( 'string', 'number', 'integer', 'boolean' ), true ) ) {
-				// The return value of get_metadata will always be a string for scalar types.
-				$sanitized = (string) $sanitized;
-			}
-
-			if ( $sanitized === $old_value[0] ) {
 			return true;
 		}
-		}
 
 		if ( ! update_metadata( $meta_type, $object_id, wp_slash( $meta_key ), wp_slash_strings_only( $value ) ) ) {
 			return new WP_Error(
@@ -389,6 +387,29 @@ abstract class WP_REST_Meta_Fields {
 		return true;
 	}
 
+	/**
+	 * Checks if the user provided value is equivalent to a stored value for the given meta key.
+	 *
+	 * @since 5.5.0
+	 *
+	 * @param string $meta_key     The meta key being checked.
+	 * @param string $subtype      The object subtype.
+	 * @param mixed  $stored_value The currently stored value retrieved from get_metadata().
+	 * @param mixed  $user_value   The value provided by the user.
+	 * @return bool
+	 */
+	protected function is_meta_value_same_as_stored_value( $meta_key, $subtype, $stored_value, $user_value ) {
+		$args      = $this->get_registered_fields()[ $meta_key ];
+		$sanitized = sanitize_meta( $meta_key, $user_value, $this->get_meta_type(), $subtype );
+
+		if ( in_array( $args['type'], array( 'string', 'number', 'integer', 'boolean' ), true ) ) {
+			// The return value of get_metadata will always be a string for scalar types.
+			$sanitized = (string) $sanitized;
+		}
+
+		return $sanitized === $stored_value;
+	}
+
 	/**
 	 * Retrieves all the registered meta fields.
 	 *

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.5-alpha-47942';
+$wp_version = '5.5-alpha-47943';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.