Gravity Forms: File Upload Url to Custom Field

<?php

// file upload url to custom field on form submission
add_action("gform_post_submission", "update_form_post_meta", 10, 2);
function update_form_post_meta($entry, $form) {

    if($form['id'] != 1) return;

    update_post_meta($entry["post_id"], 'file_url', $entry[29]);

}

?>