WordPress: Load a template file on singe-post-type page (if applicable)

template-include.php

<?php 
/**
 * Load a template file on single-post-type page (if applicable)
 *
 * Works for all post-types
 */
function dbdb_include_post_template($template) {
    if( !is_archive() ) {
        $id = get_queried_object_id();
        $template_name = get_post_meta($id, '_wp_page_template', true);
        $new_template = locate_template($template_name);

        if('' != $new_template)
            $template = $new_template;
    }
    return $template;
}

add_filter( 'template_include', 'dbdb_include_post_template' );