下面是一些关于如何简单地利用gform_after_submission 重力钩子表单，用于根据提交的表单ID设置cookie，然后在确认页面上通过钩子template_redirect.

为了自定义功能，您需要查看以下文档：setcookie, gform_after_submission 和template_redirect.

For the form

// Make sure to swap out {your_form_id} with the ID of the form.

add_action( \'gform_after_submission_{your_form_id}\', \'wpse_set_submitted_cookie\', 10, 2 );

function wpse_set_submitted_cookie( $entry, $form ) {

    // Set a third parameter to specify a cookie expiration time, 
    // otherwise it will last until the end of the current session.

    setcookie( \'wpse_form_submitted\', \'true\' );
}

add_action( \'template_redirect\', \'wpse_protect_confirmation_page\' );

function wpse_protect_confirmation_page() {
    if( is_page( \'my-confirmation-page\' ) && ! isset( $_COOKIE[\'wpse_form_submitted\'] ) ) {
        wp_redirect( home_url( \'/my-form/\' ) );
        exit();
    }
}