After the checkout is completed I want to get the promotion code that was used by the user (if any) and add it to my database.

In my stripe webhook I have the code below. If I remove the promotion code, then the order is added to my database correctly. With the promotion code, nothing is added.

I’ve gone through the docs and I can’t really figure out what i’m doing wrong?

The stripe webhook is delivered successfully and doesn’t show any errors. I appreciate any help 🙂

switch ($event->type) {
case 'checkout.session.completed':
    $sessionMain = $event->data->object;
    $checkoutID = $sessionMain->id;

    try {
        $session = StripeCheckoutSession::retrieve([
            'id' => $checkoutID,
            'expand' => ['total_details.breakdown'],
        ]);
      
        $promotionCode = $session->total_details->breakdown->discounts->discount->coupon->name;

        $sql = "INSERT INTO orders (customer_email, discount_code) VALUES (?, ?)";
        $stmt = $conn->prepare($sql);
        $stmt->bind_param("ss", $customer_email, $promotionCode);

        if ($stmt->execute()) {
            http_response_code(200);
        } else {
            error_log('Database insert failed: ' . $stmt->error);
            http_response_code(500);
        }

        $stmt->close();
    } catch (Exception $e) {
        // Log general errors
        error_log('General error: ' . $e->getMessage());
        http_response_code(500);
    }