title: PayPal IPN: custom field not passing to IPN
body: <p>I have a paypal buy button that looks like this:</p>
  
  <pre><code>&lt;form action="https://www.paypal.com/cgi-bin/webscr" method="post"&gt; 
  
  &lt;input type="hidden" name="business" value="my@email.com"&gt;
  &lt;input type="hidden" name="cmd" value="_cart"&gt;
  &lt;input type="hidden" name="upload" value="1"&gt;
  
  &lt;input type="hidden" name="item_name_1" value="item1"&gt;
  &lt;input type="hidden" name="amount_1" value="3"&gt;
  &lt;input type="hidden" name="item_name_2" value="item2"&gt;
  &lt;input type="hidden" name="amount_2" value="5"&gt;
  
  &lt;input type="hidden" name="custom" value="Admin|2"&gt;
  &lt;input type="hidden" name="discount_rate_cart" value="5"&gt;
  &lt;input type="hidden" name="notify_url" value="paypal-ipn.php"&gt;
  &lt;input type="hidden" name="currency_code" value="EUR"&gt; 
  &lt;input type="hidden" name="return" value="Thank-you-page"&gt;
  &lt;input type="hidden" name="country" value="SE"&gt;
  
  &lt;input type="submit" value="Checkout" id="checkoutButton"&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>And a IPN that looks like this:</p>
  
  <pre><code>&lt;?php
  session_start();
  
  // STEP 1: read POST data
  
  // Reading POSTed data directly from $_POST causes serialization issues with array data in the POST.
  // Instead, read raw POST data from the input stream. 
  $raw_post_data = file_get_contents('php://input');
  $raw_post_array = explode('&amp;', $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 IPN message sent from PayPal and prepend 'cmd=_notify-validate'
  $req = 'cmd=_notify-validate';
  if(function_exists('get_magic_quotes_gpc'))
  {
      $get_magic_quotes_exists = true;
  } 
  foreach ($myPost as $key =&gt; $value)
  {        
      if($get_magic_quotes_exists == true &amp;&amp; get_magic_quotes_gpc() == 1)
      { 
          $value = urlencode(stripslashes($value)); 
      }
      else
      {
          $value = urlencode($value);
      }
  
      $req .= "&amp;$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);
  
  if(strcmp($res, "VERIFIED") == 0)
  {
      // The IPN is verified, process it:
      // 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 the notification
  
      // assign posted variables to local variables
  
  
      $custom = explode('|', $_POST['custom']);
      $user = $custom['0'];
      $itemAmount = $custom['1'];
  
      $item_name = "";
  
      for($i = 0 ; $i &lt; $itemAmount ; $i++)
      {
          $item_name .= $_POST['item_name_' . ($i + 1)] . '&lt;br&gt;';
      }
  
      $payment_status = $_POST['payment_status'];
      $payment_amount = $_POST['mc_gross'] . ' ' . $_POST['mc_currency'];
      $txn_id = $_POST['txn_id'];
      $receiver_email = $_POST['receiver_email'];
      $payer_email = $_POST['payer_email'];
      $accstatus = $_POST['payer_status'];
  
      include("../config.php");
  
      $sql = "INSERT INTO `purchase` (`product`,`member`,`amount`,`ppmail`,`accstatus`,`status`)
      VALUES
      ('$item_name','$user','$payment_amount','$payer_email','$accstatus','$payment_status')";
  
      if (!mysql_query($sql,$con))
      {
          die('Error: ' . mysql_error());
      }
  
      $post_data_string = serialize($_POST);
      mail('mail@domain.com', 'PayPal IPN', $post_data_string);
  
      mysql_close($con);
  
      // IPN message values depend upon the type of notification sent.
      // To loop through the &amp;_POST array and print the NV pairs to the screen:
      foreach($_POST as $key =&gt; $value)
      {
          echo $key." = ". $value."&lt;br&gt;";
      }
  }
  else if(strcmp($res, "INVALID") == 0)
  {
      // IPN invalid, log for manual investigation
      echo "The response from IPN was: &lt;b&gt;" .$res ."&lt;/b&gt;";
  }
  ?&gt;
  </code></pre>
  
  <p>Now why does not the custom field get passed on to the API?</p>
  
  <p>I do get this in error logging, because custom[0] = "" and custom[1] does not exist:</p>
  
  <pre><code>HP Notice:  Undefined offset: 1 in /home1/planetzi/public_html/firefallcrystite/action/paypal-ipn.php on line 79
  </code></pre>