WordPress replace page template based on url

add_filter( 'template_include', 'portfolio_page_template', 999 );
function portfolio_page_template( $template ) {
 $url = 'https://' . $_SERVER['SERVER_NAME'] . $_SERVER['REQUEST_URI'];
    if (strpos($url,'slideshow') !== false) {
        $new_template = locate_template( array( 'slideshow.php' ) );
    if ( '' != $new_template ) {
        return $new_template ;
    }
    }
    return $template;
}