Facebook Pay Dialog not returning resposnse - facebook

Question

I'm trying to open a Pay Dialog and it's not going well. When I set the action to buy_credits or ear_credits it works. But when I set action to buy_item it returns an error of"
1383046 - Sorry, but we're having trouble processing your payment. You have not been charged for this transaction. Please try again.
My Java Code:
<script type="text/javascript">
function buy() {
FB.ui(
{
method: 'pay',
action: 'buy_item',
order_info: { 'item_id': '1a'},
dev_purchase_params: {'oscif': true}
},
js_callback);
}
var js_callback = function (data) {
if (data['order_id']) {
write_callback_data(
"<br><b>Transaction Completed!</b> </br></br>"
+ "Data returned from Facebook: </br>"
+ "Order ID: " + data['order_id'] + "</br>"
+ "Status: " + data['status']);
} else if (data['error_code']) {
// Appropriately alert the user.
write_callback_data(
"<br><b>Transaction Failed!</b> </br></br>"
+ "Error message returned from Facebook:</br>"
+ data['error_code'] + " - "
+ data['error_message']);
} else {
// Appropriately alert the user.
write_callback_data("<br><b>Transaction failed!</b>");
}
};
function write_callback_data(str) {
document.getElementById('fb-ui-return-data').innerHTML = str;
}
</script>
My PHP callback code:
error_reporting(E_ALL);
$app_secret = '********************************';
// Validate request is from Facebook and parse contents for use.
$request = parse_signed_request($_POST['signed_request'], $app_secret);
// Get request type.
// Two types:
// 1. payments_get_items.
// 2. payments_status_update.
$request_type = $_POST['method'];
error_log($request_type, 0);
// Setup response.
$response = '';
if ($request_type == 'payments_get_items') {
// Get order info from Pay Dialog's order_info.
// Assumes order_info is a JSON encoded string.
$order_info = json_decode($request['credits']['order_info'], true);
// Get item id.
$item_id = $order_info['item_id'];
// Simulutates item lookup based on Pay Dialog's order_info.
if ($item_id == '1a') {
$item = array(
'title' => '100 Gold',
'description' => 'Premium Currency.',
// Price must be denominated in credits.
'price' => 5,
'image_url' => '1a.png'
);
// Construct response.
$response = array(
'content' => array(
0 => $item,
),
'method' => "payments_get_items",
);
// Response must be JSON encoded.
$response = json_encode($response);
}
} else if ($request_type == "payments_status_update") {
// Get order details.
$order_details = json_decode($request['credits']['order_details'], true);
// Determine if this is an earned currency order.
$item_data = json_decode($order_details['items'][0]['data'], true);
$earned_currency_order = (isset($item_data['modified'])) ?
$item_data['modified'] : null;
// Get order status.
$current_order_status = $order_details['status'];
if ($current_order_status == 'placed') {
// Fulfill order based on $order_details unless...
if ($earned_currency_order) {
// Fulfill order based on the information below...
// URL to the application's currency webpage.
$product = $earned_currency_order['product'];
// Title of the application currency webpage.
$product_title = $earned_currency_order['product_title'];
// Amount of application currency to deposit.
$product_amount = $earned_currency_order['product_amount'];
// If the order is settled, the developer will receive this
// amount of credits as payment.
$credits_amount = $earned_currency_order['credits_amount'];
}
$next_order_status = 'settled';
// Construct response.
$response = array(
'content' => array(
'status' => $next_order_status,
'order_id' => $order_details['order_id'],
),
'method' => $request_type,
);
// Response must be JSON encoded.
$response = json_encode($response);
} else if ($current_order_status == 'disputed') {
// 1. Track disputed item orders.
// 2. Investigate user's dispute and resolve by settling or refunding the order.
// 3. Update the order status asychronously using Graph API.
} else if ($current_order_status == 'refunded') {
// Track refunded item orders initiated by Facebook. No need to respond.
} else {
// Track other order statuses.
}
}
// Send response.
error_log(print_r($response, true));
echo $response;
// These methods are documented here:
// https://developers.facebook.com/docs/authentication/signed_request/
function parse_signed_request($signed_request, $secret) {
list($encoded_sig, $payload) = explode('.', $signed_request, 2);
// decode the data
$sig = base64_url_decode($encoded_sig);
$data = json_decode(base64_url_decode($payload), true);
if (strtoupper($data['algorithm']) !== 'HMAC-SHA256') {
error_log('Unknown algorithm. Expected HMAC-SHA256');
return null;
}
// check sig
$expected_sig = hash_hmac('sha256', $payload, $secret, $raw = true);
if ($sig !== $expected_sig) {
error_log('Bad Signed JSON signature!');
return null;
}
return $data;
}
function base64_url_decode($input) {
return base64_decode(strtr($input, '-_', '+/'));
}
I have error_log calls in the script and it seems when I press the buy button it calls the service twice. Calling the same method: payments_get_items. The response data looks like it is properly formatted. Here is the output of the log:
payments_get_items
{"content":[{"title":"100 Gold","description":"Premium Currency.","price":5,"image_url":"1a.png"}],"method":"payments_get_items"}
payments_get_items
{"content":[{"title":"100 Gold","description":"Premium Currency.","price":5,"image_url":"1a.png"}],"method":"payments_get_items"}

Answer 1

This is almost certainly a problem with the response your callback URL is returning to Facebook.
The reason you see two entries is that Facebook will try twice to get a (valid) response before failing, and giving the user the 'Sorry, but we're having trouble processing your payment...' error message.
Check the HTTP error codes and the body of the response you're giving to Facebook and make sure it's valid