Ticket #43941: 43941.3.diff

src/wp-includes/meta.php

@@ -536 +536 @@
                 }
         }
 
+        return get_metadata_default( $meta_type, $meta_key, $single, $object_id );
+}
+
+/**
+ * Retrieve metadata data default for the specified object.
+ *
+ * @since 5.2.0
+ *
+ * @param string $meta_type Type of object metadata is for (e.g., comment, post, term, or user).
+ * @param string $meta_key  Optional. Metadata key. If not specified, retrieve all metadata for
+ *                          the specified object.
+ * @param bool   $single    Optional, default is false.
+ *                          If true, return only the first value of the specified meta_key.
+ *                          This parameter has no effect if meta_key is not specified.
+ * @param int    $object_id Optional, default is 0.
+ *                          ID of the object metadata is for
+ * @return mixed Single metadata value, or array of values
+ */
+function get_metadata_default( $meta_type, $meta_key, $single = false, $object_id = 0 ) {
         if ( $single ) {
-                return '';
+                $value = '';
         } else {
-                return array();
+                $value = array();
         }
+
+        /**
+         *
+         * @since 5.2.0
+         *
+         * @param array|string      $value     The value should return - a single metadata value,
+         *                                     or an array of values.
+         * @param string            $meta_type Type of object metadata is for (e.g., comment, post, term, or user).
+         * @param string            $meta_key  Meta key.
+         * @param bool              $single    Whether to return only the first value of the specified $meta_key.
+         * @param int               $object_id Object ID.
+         */
+        $value = apply_filters( "default_{$meta_type}_metadata", $value, $meta_type, $meta_key, $single, $object_id );
+
+        return $value;
 }
 
 /**
@@ -1141 +1175 @@
                 'type'              => 'string',
                 'description'       => '',
                 'single'            => false,
+                'default'           => null,
                 'sanitize_callback' => null,
                 'auth_callback'     => null,
                 'show_in_rest'      => false,
@@ -1206 +1241 @@
                 }
         }
 
+        if ( false === $args['single'] && ! wp_is_numeric_array( $args['default'] ) ) {
+                $args['default'] = null;
+        }
+
+        if ( null !== $args['default'] ) {
+                add_filter( "default_{$object_type}_metadata", "filter_default_metadata", 10, 5 );
+        }
+
         // Global registry only contains meta keys registered with the array of arguments added in 4.6.0.
         if ( ! $has_old_auth_cb && ! $has_old_sanitize_cb ) {
                 unset( $args['object_subtype'] );
@@ -1434 +1477 @@
          */
         return apply_filters( "get_object_subtype_{$object_type}", $object_subtype, $object_id );
 }
+
+/**
+ *
+ * @param $value
+ * @param $meta_type
+ * @param $meta_key
+ * @param $single
+ * @param $object_id
+ *
+ * @return mixed
+ */
+function filter_default_metadata( $value, $meta_type, $meta_key, $single, $object_id ) {
+        $metadata = get_registered_meta_keys( $meta_type );
+        if ( ! isset( $metadata[ $meta_key ] ) ) {
+                $sub_type = get_object_subtype( $meta_type, $object_id );
+                $metadata = get_registered_meta_keys( $meta_type, $sub_type );
+                if ( ! isset( $metadata[ $meta_key ] ) ) {
+                        return $value;
+                }
+        }
+
+        if ( $metadata[ $meta_key ]['single'] ) {
+                if ( $single ) {
+                        $value = $metadata[ $meta_key ]['default'];
+                } else {
+                        $value = array( $metadata[ $meta_key ]['default'] );
+                }
+        } else {
+                if ( $single ) {
+                        $value = $metadata[ $meta_key ]['default'][0];
+                } else {
+                        $value = $metadata[ $meta_key ]['default'];
+                }
+        }
+
+        return $value;
+}
+ No newline at end of file