Sending a serialized and url encoded array through Paypal and out again through IPN

Hi there

I have a multiple page form that collects data and sends it to another page where the user can review the submitted data and use a Paypal buy button to purchase my service.

I've set up an IPN script that is successfully emailing me once a purchase has been made, however, I also need it to send me the values from the multiple page form mentioned before.

As I understand it, you are only allowed one custom field associated with a Paypal button - named "custom"; so I need to put the values for my entire form through Paypal using this one field.

I have turned the form variables into a string and passed that through, successfully, although I need to be able to split the variables out again on my IPN listener page and display them in an mail, one on each line preceeded with some text.
eg Email: $submit['email'];\n
     Domain: $submit['domain'];

I think I need to pass the values through as an array, rather than a string, so I can pull the separate values out of the array at the other end.  I've tried to serialize the array, and encode and then serialize (and decode/deserialize at the other end) but it's just coming out blank.
I think I also need to pull the values out of the array and set them as variables before I can use them in the mail function.

I've tried a great deal of things to try and get this to work, but I think most of what I've tried is equally wrong/incorrect as what I've got at the moment, so there's no point in me trying to list it all!

(One thing to note, though; when I use serialize and then unserialize on the page with the Paypal button, it works fine, but if I encode and then decode while serializing/unserializing, I always get a blank output.  Taking the encode/decode out of the array to pass through Paypal is making no difference, so I've left it in as I think this is the correct way to do it.)


I've pasted relevant bits of my code below.


Thanks in advance!

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/////// The page with the Paypal button ///////
 
///// Top of the page
 
// Turn into an array
$signup = array('email' => $email, 'firstname' => $firstname, 'lastname' => $lastname, 'company' => $company, 'domain' => $domain, 'extension' => $extension, 'template' => $template,  'banner' => $banner);
 
// Serialize and encode it
$signup_s = urlencode(serialize($signup));
 
///// Within the Paypal button form
 
<input type="hidden" name="custom" value="<?php echo $signup_s ?>" />
 
 
 
/////// The Paypal IPN listener page ///////
 
// Decoding and unserializing the array
$signup = urldecode(unserialize($_POST['custom'])); 
 
// Printing the array into the body of the mail
$mail_Body = print_r($signup, true);
mail($mail_To, $mail_Subject, $mail_Body, $mail_From);