At first glance it looks like you need to add your save routine to a hook, which in this case would save_post
.
function __construct() {
add_action( 'add_meta_boxes', array( $this, 'create_fields_array') );
add_action( 'load-post.php', array( $this,'setup_boxes') );
add_action( 'load-post-new.php', array( $this, 'setup_boxes') );
add_action( 'admin_enqueue_scripts', array($this, 'load_scripts') );
//don't forget the save routine
add_action( 'save_post', array($this, 'save_meta') );
}
This is making the assumption that your save_meta()
function is in the class and that your class is being properly instantiated.