Working with Database Transactions in Eloquent

// Example in a controller method or service class
use Illuminate\Support\Facades\DB;
use App\Models\Order;
use App\Models\Product;
use Exception;

class OrderService
{
    public function createOrder(array $orderData, array $productQuantities)
    {
        DB::beginTransaction();

        try {
            // 1. Create the order
            $order = Order::create([ 
                'user_id' => $orderData['user_id'],
                'total_amount' => 0 // Will be updated later
            ]);

            $totalAmount = 0;

            // 2. Attach products to the order and update inventory
            foreach ($productQuantities as $productId => $quantity) {
                $product = Product::find($productId);

                if (!$product || $product->stock < $quantity) {
                    throw new Exception("Product {$productId} not found or insufficient stock.");
                }

                $order->products()->attach($productId, ['quantity' => $quantity, 'price' => $product->price]);
                $product->decrement('stock', $quantity);
                $totalAmount += ($product->price * $quantity);
            }

            // 3. Update the order total amount
            $order->update(['total_amount' => $totalAmount]);

            DB::commit(); // All operations successful, commit the transaction

            return $order;

        } catch (Exception $e) {
            DB::rollBack(); // Something went wrong, rollback all operations
            // Optionally, log the error or re-throw
            throw $e;
        }
    }
}

// Using the service in a controller:
// $orderService = new OrderService();
// try {
//     $order = $orderService->createOrder(
//         ['user_id' => 1],
//         [1 => 2, 3 => 1] // Product ID => Quantity
//     );
//     return response()->json(['message' => 'Order placed successfully', 'order_id' => $order->id]);
// } catch (Exception $e) {
//     return response()->json(['error' => $e->getMessage()], 400);
// }