How to rename uploaded files with additional data?

[Mati Roosalu]

I use jQuery-File_upload basic version for picture order module.

In main index.html file I add select:

<!-- The template to display files available for upload -->

<script id="template-upload" type="text/x-tmpl">

{% for (var i=0, file; file=o.files[i]; i++) { %}

    <tr class="template-upload fade">

        <td>

            <span class="preview"></span>

        </td>

        <td align="left">Vajadusel muuda kogust</p>

<select id="soflows" name="quantity[]">

  <option value="1P.C">1</option>

  <option value="2P.C">2</option>

  <option value="3P.C">3</option>

  <option value="4P.C">4</option>

  <option value="5P.C">5</option>

  <option value="6P.C">6</option>

  <option value="7P.C">7</option>

  <option value="8P.C">8</option>

  <option value="9P.C">9</option>

</select>

            <p class="name">{%=file.name%}</p>

In server/php/index.php I add rename function:

error_reporting(E_ALL | E_STRICT);

require('UploadHandler.php');

class CustomUploadHandler extends UploadHandler {

protected function handle_form_data($file, $index) {

        // Handle form data, e.g. $_POST['description'][$index]

//$amount = $_POST['quantity'][$index];

    }

protected function trim_file_name($file_path, $name, $size, $type, $error, $index, $content_range) {

$amount = $_REQUEST['quantity'][$index];

$name = $amount . '-' . $name;

return $name;

}

}

//$upload_handler = new UploadHandler();

$upload_handler = new CustomUploadHandler();

Typical scenario:

client add files 564.jpg; 565.jpg; 566... e.t.c and would like to order a different amount of photos

Client selects

564.jpg - quantity 2

565.jpg - quantity 3

566.jpg - quantity 1

etc.

I need result - new uploaded filenames 

2PC-564.jpg

3PC-565.jpg

1PC-566.jpg

Yeah, I get it but only in this case if client upload files with small button - "Start" and send all files separately.

If client use button "Start upload" to send them all at once I have problem.

With js/jquery.fileupload.js default options settings I have wrong result:

2PC-564.jpg

2PC-565.jpg

2PC-566.jpg

Can anyone recommend something?