GoogleCloudPlatform/microservices-demo · error

failed to get user cart during checkout: %+v

Error message

failed to get user cart during checkout: %+v

What it means

getUserCart wraps a failed CartService.GetCart gRPC call with this message. Checkout could not read the user's cart, so the order cannot be built. Typical root causes are cart service unavailability or an invalid/empty user ID.

Source

Thrown at src/checkoutservice/main.go:327

	out.orderItems = orderItems
	return out, nil
}

func (cs *checkoutService) quoteShipping(ctx context.Context, address *pb.Address, items []*pb.CartItem) (*pb.Money, error) {
	shippingQuote, err := pb.NewShippingServiceClient(cs.shippingSvcConn).
		GetQuote(ctx, &pb.GetQuoteRequest{
			Address: address,
			Items:   items})
	if err != nil {
		return nil, fmt.Errorf("failed to get shipping quote: %+v", err)
	}
	return shippingQuote.GetCostUsd(), nil
}

func (cs *checkoutService) getUserCart(ctx context.Context, userID string) ([]*pb.CartItem, error) {
	cart, err := pb.NewCartServiceClient(cs.cartSvcConn).GetCart(ctx, &pb.GetCartRequest{UserId: userID})
	if err != nil {
		return nil, fmt.Errorf("failed to get user cart during checkout: %+v", err)
	}
	return cart.GetItems(), nil
}

func (cs *checkoutService) emptyUserCart(ctx context.Context, userID string) error {
	if _, err := pb.NewCartServiceClient(cs.cartSvcConn).EmptyCart(ctx, &pb.EmptyCartRequest{UserId: userID}); err != nil {
		return fmt.Errorf("failed to empty user cart during checkout: %+v", err)
	}
	return nil
}

func (cs *checkoutService) prepOrderItems(ctx context.Context, items []*pb.CartItem, userCurrency string) ([]*pb.OrderItem, error) {
	out := make([]*pb.OrderItem, len(items))
	cl := pb.NewProductCatalogServiceClient(cs.productCatalogSvcConn)

	for i, item := range items {
		product, err := cl.GetProduct(ctx, &pb.GetProductRequest{Id: item.GetProductId()})
		if err != nil {

View on GitHub (pinned to 72ba613a05)

Solutions

1. Check cartservice pods/logs and its Redis backend connectivity.
2. Verify userID is non-empty and valid before calling PlaceOrder (fail fast with InvalidArgument).
3. Check the gRPC status code: Unavailable -> retry with backoff; InvalidArgument -> fix the caller.
4. Confirm DNS/network policies allow checkoutservice to reach cartservice.

Example fix

// before
cart, err := pb.NewCartServiceClient(cs.cartSvcConn).GetCart(ctx, &pb.GetCartRequest{UserId: userID})
if err != nil {
	return nil, fmt.Errorf("failed to get user cart during checkout: %+v", err)
}
// after
if userID == "" {
	return nil, status.Error(codes.InvalidArgument, "user ID is required to fetch the cart")
}
cart, err := pb.NewCartServiceClient(cs.cartSvcConn).GetCart(ctx, &pb.GetCartRequest{UserId: userID})
if err != nil {
	return nil, fmt.Errorf("failed to get user cart during checkout: %w", err)
}

if userID == "" {
	return status.Error(codes.InvalidArgument, "user ID is required")
}
// optionally probe cart service health first
resp, err := cartConn.Invoke(ctx, healthCheckMethod, ...) // or use grpc health protocol

func isLoggedIn(userID string) bool {
	return userID != "" // extend with session validation
}

cart, err := cartClient.GetCart(ctx, req)
if err != nil {
	if status.Code(err) == codes.Unavailable {
		return retryWithBackoff(ctx, req)
	}
	return fmt.Errorf("failed to get user cart during checkout: %w", err)
}

When it happens

Trigger: pb.NewCartServiceClient(cs.cartSvcConn).GetCart(ctx, &pb.GetCartRequest{UserId: userID}) errors: cartservice down, unknown user ID rejected, or context deadline/cancellation.

Common situations: cartservice (often Redis-backed) crashed or lost its Redis connection; user ID empty because session/auth failed upstream; network policy blocking checkout->cart traffic.

Related errors

• failed to empty user cart during checkout: %+v
• could not retrieve cart
• failed to add to cart
• failed to empty cart
• FAILED_PRECONDITION

AI-assisted analysis of GoogleCloudPlatform/microservices-demo@72ba613a05 (2026-09-02). Data as JSON: /api/errors/1aca465002a02d53. Report an issue: GitHub.