使用PHP中的PayPal IPN抓取自定义字段

So on my website, people are able to order upgrades by clicking "Pay Now" for the upgrade they want and by entering their username in the box. Up until now, I would then go in to PayPal, see the payment, and look at the Minecraft Username field, and upgrade it by hand. Now I want to start using IPN so that I can automate all of the work that i've been doing.

Here is the HTML code for a upgrade option:

<div class=donationBox>

<form action="https://www.paypal.com/cgi-bin/webscr" method="post">
<input type="hidden" name="cmd" value="_s-xclick">
<input type="hidden" name="hosted_button_id" value="W2RH7VA3YS3Y4">
<table>
<tr>
<td width=75%><h2>Custom Maps - $5.00</h2></td>
<td><input type="hidden" name="on0" value="Minecraft Username">Minecraft Username<input type="text" name="os0" maxlength="200"></td>
</tr>
<tr>

<td>The ability to upload any map you want to play on! Maybe a survival island map? You bet! Or the Hunger Games!</td>
<td><input type="submit" class="btn btn-primary" value="Buy Now" border="0" name="submit" alt="PayPal - The safer, easier way to pay online!"></td>
</tr>
</table>
</form>
</div>

And here is the PHP code to simply send me an Email with the info I need to try to get it working:

  <?php

  // STEP 1: Read POST data

  // reading posted data from directly from $_POST causes serialization 
  // issues with array data in POST
  // reading raw POST data from input stream instead. 
  $raw_post_data = file_get_contents('php://input');
  $raw_post_array = explode('&', $raw_post_data);
  $myPost = array();
  foreach ($raw_post_array as $keyval) {
    $keyval = explode ('=', $keyval);
    if (count($keyval) == 2)
       $myPost[$keyval[0]] = urldecode($keyval[1]);
  }
  // read the post from PayPal system and add 'cmd'
  $req = 'cmd=_notify-validate';
  if(function_exists('get_magic_quotes_gpc')) {
     $get_magic_quotes_exists = true;
  } 
  foreach ($myPost as $key => $value) {        
     if($get_magic_quotes_exists == true && get_magic_quotes_gpc() == 1) { 
          $value = urlencode(stripslashes($value)); 
     } else {
          $value = urlencode($value);
     }
     $req .= "&$key=$value";
  }


  // STEP 2: Post IPN data back to paypal to validate

  $ch = curl_init('https://www.paypal.com/cgi-bin/webscr');
  curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
  curl_setopt($ch, CURLOPT_POST, 1);
  curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
  curl_setopt($ch, CURLOPT_POSTFIELDS, $req);
  curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 1);
  curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
  curl_setopt($ch, CURLOPT_FORBID_REUSE, 1);
  curl_setopt($ch, CURLOPT_HTTPHEADER, array('Connection: Close'));

  // In wamp like environments that do not come bundled with root authority certificates,
  // please download 'cacert.pem' from "http://curl.haxx.se/docs/caextract.html" and set the directory path 
  // of the certificate as shown below.
  // curl_setopt($ch, CURLOPT_CAINFO, dirname(__FILE__) . '/cacert.pem');
  if( !($res = curl_exec($ch)) ) {
      // error_log("Got " . curl_error($ch) . " when processing IPN data");
      curl_close($ch);
      exit;
  }
  curl_close($ch);


  // STEP 3: Inspect IPN validation result and act accordingly

  if (strcmp ($res, "VERIFIED") == 0) {
  // check whether the payment_status is Completed
  // check that txn_id has not been previously processed
  // check that receiver_email is your Primary PayPal email
  // check that payment_amount/payment_currency are correct
  // process payment

  // assign posted variables to local variables
  $item_name = $_POST['item_name'];
  $item_number = $_POST['item_number'];
  $payment_status = $_POST['payment_status'];
  $payment_amount = $_POST['mc_gross'];
  $payment_currency = $_POST['mc_currency'];
  $txn_id = $_POST['txn_id'];
  $receiver_email = $_POST['receiver_email'];
  $payer_email = $_POST['payer_email'];
  $custom = $_POST['on0'];
  $message = "An order has been IPNified! " . $item_name . " " . $item_number . " " . $payment_amount . " " . $txn_id . " " . $custom;
  mail('myemail@gmail.com', 'PayPal IPN', $message);
  } else if (strcmp ($res, "INVALID") == 0) {
      mail('myemail@gmail.com', 'PayPal IPN', 'Errors');
  }
  ?>

The problem that I'm having is here:

$custom = $_POST['on0'];

I tried it as the above and:

$custom = $_POST['custom'];

The first one because that's the name of the Minecraft Username field, and the second I tried because I read that's what it should be, but either way it just didn't return anything. Any help would be great! Thanks!

Dump the results of $_POST and see which key fits the values you're looking for. Use either var_dump or print_r

// Displays more detail such as value types
var_dump($_POST);

// Only displays key => value relationships of an array
print_r($_POST);

EDIT

I just realized it's not possible to see the output of this using ipn. In this case you can always serialize the entire $_POST array and send it in an email.

$post_data_string = serialize($_POST);
mail('myemail@gmail.com', 'PayPal IPN', $post_data_string);

First, you're using a hosted button. As such, any custom options you set must be done within the button creation wizard or edit area of your PayPal account.

The actual parameter name for sending custom data is indeed "custom" so that's what you'll need to use in IPN to get values back for that particular parameter.

What was mentioned before (changing the field name on your form to custom) would work except that you're using a hosted button, so again, that will need to be adjusted in the button manager in your PayPal account.