Step I - Modify function getFilename()

Open and edit function getFilename() in your-website/classes/pdf/HTMLTemplateInvoice.php by using your favourite editor.

Step II - Get the customer object : Find getFilename() function (line 500):

  public function getFilename()
      {
          $id_lang = Context::getContext()->language->id;
          $id_shop = (int)$this->order->id_shop;
          $format = '%1$s%2$06d';
  

Change it to:

  public function getFilename()
      {
          $id_lang = Context::getContext()->language->id;
          $id_shop = (int)$this->order->id_shop;
          $format = '%1$s%2$06d';
          $customer = new Customer((int)$this->order->id_customer);
  

Step III - Return with the name and the number

Look into this code:

  return sprintf(
              $format,
              Configuration::get('PS_INVOICE_PREFIX', $id_lang, null, $id_shop),
              $this->order_invoice->number,
              date('Y', strtotime($this->order_invoice->date_add))
          ).'.pdf';
  

Change it to:

  return sprintf(
              $format,
              Configuration::get('PS_INVOICE_PREFIX', $id_lang, null, $id_shop),
              $this->order_invoice->number,
              date('Y', strtotime($this->order_invoice->date_add))
          ).'_'.$customer->firstname.'_'.$customer->lastname.'.pdf';
  

Final - Enjoy your result

The generated invoice name will be IN_number_customername.pdf. For example IN000001_Natalia_Eva.pdf. We also released a new module called DocumenThemix to help you to customize and personalize the Prestashop Invoice template as well as Delivery Slip & Credit Slip. You should take a view on it and try for a while - it's powerful and easy to use.

Is it cool, huh? Don't forget our blog to find useful Prestashop tutorials.