CPT Redirect

cpt-redirect.php

<?php

define( 'MY_CPT', 'actor' );

/**
 * Redirects /cary-grant/ to /actor/cary-grant/ or whatever the correct URL is
 */
function redirect_old_cpt_urls() {
	if ( !is_404() )
		return;

	global $wp_query, $wpdb;

	if ( empty( $wp_query->query['pagename'] ) || false !== strpos( $wp_query->query['pagename'], '/' ) )
		return;

	$args = array(
		'fields' => 'ids',
		'post_type' => MY_CPT,
		'name' => $wp_query->query['pagename']
	);

	$posts = get_posts( $args );

	if ( count( $posts ) == 1 ) {
		wp_redirect( get_permalink( $posts[0] ) . $get_params, 301 );
		exit();
	}
}
add_action( 'template_redirect', 'redirect_old_cpt_urls', 9 );