看起来我是用这个类来做这个的：http://gravitywiz.com/rename-uploaded-files-for-gravity-form/ 并在207行之后添加了过滤器，即。

    // replace merge tags
    $form  = GFAPI::get_form( $entry[\'form_id\'] );
    $value = GFCommon::replace_variables( $value, $form, $entry, false, true, false, \'text\' );

    // MOD: add a filter here to hook into filename change
    $value = apply_filters(\'gravity_forms_upload_filename\', $value, $entry);

这是我用来加载的代码段GW_Rename_Uploaded_Files:

add_action(\'init\', \'my_forms_rename_uploads\', 11);
if (!function_exists(\'my_forms_rename_uploads\')) {
 function my_forms_rename_uploads() {
    if (!class_exists(\'GW_Rename_Uploaded_Files\')) {return;}
    $form_ids = array(
        1, // list of form IDs to load renaming class for
    );

    // --- get all file upload fields ---
    foreach ($form_ids as $form_id) {
        $upload_field_ids = array();
        $form = GFFormsModel::get_form_meta($form_id);
        if (isset($form[\'fields\'])) {
            // --- get upload field IDs ---
            foreach ($form[\'fields\'] as $field) {
                if ($field->type == \'fileupload\') {$upload_field_ids[] = $field->id;}
            }
            // --- set class arguments ---
            $args = array(
                \'form_id\' => $form_id,
                \'field_id\' => $upload_field_ids,
                \'template\' => \'{filename}\'
            );
            // --- initialize rename uploaded files class for fields ---
            new GW_Rename_Uploaded_Files($args);
        }
    }
 }
}