Ensuring Data Consistency with Eloquent Transactions

use Illuminate\Support\Facades\DB;
use App\Models\Order;
use App\Models\Product;

try {
    DB::transaction(function () {
        // Create a new order
        $order = Order::create([
            'user_id' => auth()->id(),
            'status' => 'pending',
            'total_amount' => 0, // Will be updated later
        ]);

        $totalAmount = 0;
        $items = [
            ['product_id' => 1, 'quantity' => 2],
            ['product_id' => 2, 'quantity' => 1],
        ];

        foreach ($items as $item) {
            $product = Product::find($item['product_id']);

            if (!$product || $product->stock < $item['quantity']) {
                // If product not found or not enough stock, throw an exception
                // This will trigger a rollback
                throw new \Exception('Product ' . $item['product_id'] . ' not available or insufficient stock.');
            }

            // Deduct stock
            $product->decrement('stock', $item['quantity']);

            // Add to order items and calculate total
            $order->items()->create([
                'product_id' => $product->id,
                'quantity' => $item['quantity'],
                'price' => $product->price,
            ]);
            $totalAmount += $product->price * $item['quantity'];
        }

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

        // All operations successful, transaction commits automatically
        // If any exception occurs, the transaction will be rolled back.
    });
    echo "Order placed successfully!";
} catch (\Exception $e) {
    echo "Order failed: " . $e->getMessage();
    // The transaction was automatically rolled back by DB::transaction()
}