Remove landing pages from the search results

Code to remove landing pages from site search results. Assumes that templates are in the templates directory inside the theme.

add_action( 'pre_get_posts', 'leaven_search_hide_landing_page' );
/**
 * Removes landing pages from the search results.
 *
 * @param $query \WP_Query
 *
 * @return mixed
 */
function leaven_search_hide_landing_page( $query ) {

    if ( $query->is_search && $query->is_main_query() && ! is_admin() ) {
        $query->set( 'meta_query', array(
            'relation' => 'OR',
            array(
                'key'     => '_wp_page_template',
                'compare' => 'NOT EXISTS',
            ),
            array(
                'key'     => '_wp_page_template',
                'value'   => 'templates/page_landing.php',
                'compare' => '!=',
            ),
        ) );
    }

    return $query;

}