<?php namespace Gutenberg_Courses\Example_Blocks; add_action( 'init', __NAMESPACE__ . '\register_meta_fields' ); /** * Registering meta fields for block attributes that use meta storage */ function register_meta_fields() { register_meta( 'post', 'themepunchblocks_gb_metabox', [ 'type' => 'string', 'single' => true, 'show_in_rest' => true, ] ); }