App\Http\Controllers\ClientPortalController::download PHP Method

    public function download($invitationKey)
    {
        if (!($invitation = $this->invoiceRepo->findInvoiceByInvitation($invitationKey))) {
            return response()->view('error', ['error' => trans('texts.invoice_not_found'), 'hideHeader' => true]);
        }
        $invoice = $invitation->invoice;
        $pdfString = $invoice->getPDFString();
        header('Content-Type: application/pdf');
        header('Content-Length: ' . strlen($pdfString));
        header('Content-disposition: attachment; filename="' . $invoice->getFileName() . '"');
        header('Cache-Control: public, must-revalidate, max-age=0');
        header('Last-Modified: ' . gmdate('D, d M Y H:i:s') . ' GMT');
        return $pdfString;
    }