PHP mailer and FPDF attachment with loop - script stops after first run - loops

Question

I'm running a following script to generate and send email. The email body is generated in a while loop (content differs) - it works fine. But now I have tried to include a script to generate PDF attachment (via FPDF library), in each iteration the attachment is different.
Problem is: the loop runs just once, for the first case and after it stops. Thank you for your commnents in advance.
My code:
<?
$mail = new PHPMailer();
$mail->SMTPDebug = 1;
$mail->isSMTP();
$mail->addReplyTo('');
$mail->isHTML(true);
$mail->Subject = "";
$mail->Host = 'smtp.gmail.com';
$mail->SMTPAuth = true;
$mail->SMTPSecure = 'tls';
$mail->Port = 587;
$mail->CharSet = 'utf-8';
$mail->setFrom('');
while(($data=MySQL_Fetch_Array($vysl))!=NULL) {
require_once('invoicetopdf.php');
$message="";
$mail->AddStringAttachment($invoice, 'Invoice.pdf', 'base64', 'application/pdf');
$mail->Username = "";
$mail->Password = "";
$mail->addAddress($to);
$mail->Body = $message;
if (!$mail->send()) {echo "Mailer Error: " . $mail->ErrorInfo;}
else {
$mail->clearAddresses();
$mail->ClearAllRecipients();
$mail->clearAttachments();
echo "Ok";
}
} //while
//invoicetopdf.php:
$data = MySQL_Fetch_Array($vysl);
require_once('../knihovny/pdf/fpdf.php');
$pdf = new PDF();
$pdf->.....;
$invoice=$pdf->Output('S');
?>

Answer 1

That's a bit of an odd way to run that code repeatedly. I would define a function in your invoicetopdf.php file, load it at the top of your script, and then call the function inside the loop to get the PDF data. You're also calling mysql_fetch_array twice - once in the while loop, once in the function, meaning half your data will be going astray.
require_once('invoicetopdf.php');
while(($data=MySQL_Fetch_Array($vysl))!=NULL) {
$message="";
$mail->AddStringAttachment(generatePDF($data), 'Invoice.pdf', 'base64', 'application/pdf');
...
//invoicetopdf.php:
require_once('../knihovny/pdf/fpdf.php');
function generatePDF($data) {
$pdf = new PDF();
$pdf->.....;
return $invoice=$pdf->Output('S');
}
I also recommend moving the Username and Password out of the loop, and you probably don't need to call clearAllRecipients(); clearAddresses() is enough.
Setting SMTPDebug = 2 will let you see more of what's happening in SMTP land.

Answer 2

Now it works: the main problem was a mixing a class and functions together. See:Multiple PDFs in Loop with FPDF
Thank you guys!