Laravel 10中如何自动更新restock字段：库存达最低值时设为1

需求：当商品的stock（库存）等于min_stock（最低库存）时，自动将restock字段设为1；否则设为0。

现有代码 #

数据库迁移代码

Schema::create('products', function (Blueprint $table) {
    $table->id();
    $table->string('product_name');
    $table->string('category_id');
    $table->string('unit_id');
    $table->string('product_code')->nullable();
    $table->double('min_stock');
    $table->double('stock');
    $table->integer('restock')->default(0)->comment('0=No, 1=Yes');
    $table->string('product_image')->nullable();
    $table->timestamps();
});

出库场景控制器代码

public function updateOrder(Request $request)
{
    $order_id = $request->id;

    // Reduce the stock
    $products = OrderDetails::where('order_id', $order_id)->get();

    foreach ($products as $product) {
        Product::where('id', $product->product_id)
                ->update(['stock' => DB::raw('stock-'.$product->quantity)]);
    }

    Order::findOrFail($order_id)->update(['order_status' => 'complete']);

    return Redirect::route('order.completeOrders')->with('success', 'Order has been completed!');
}

入库场景控制器代码

public function updatePurchase(Request $request)
{
    $purchase_id = $request->id;

    // after purchase approved, add stock product
    $products = PurchaseDetails::where('purchase_id', $purchase_id)->get();

    foreach ($products as $product) {
        Product::where('id', $product->product_id)
                ->update(['stock' => DB::raw('stock+'.$product->quantity)]);
    }

    Purchase::findOrFail($purchase_id)
        ->update([
            'purchase_status' => 1,
            'updated_by' => auth()->user()->id
        ]); // 1 = approved, 0 = pending

    return Redirect::route('purchases.allPurchases')->with('success', 'Purchase has been approved!');
}

实现方案 #

推荐在模型层面处理这个逻辑，这样不管通过哪种方式修改库存（控制器、后台编辑、API等），都能自动同步restock字段，避免重复代码和遗漏场景。

方案1：模型观察者（推荐）

1. 生成Product模型观察者：

php artisan make:observer ProductObserver --model=Product

2. 在app/Observers/ProductObserver.php中添加逻辑：

namespace App\Observers;

use App\Models\Product;

class ProductObserver
{
    // 在模型保存（创建/更新）前触发
    public function saving(Product $product): void
    {
        $product->restock = $product->stock == $product->min_stock ? 1 : 0;
    }
}

3. 在app/Providers/AppServiceProvider.php的boot方法中注册观察者：

use App\Models\Product;
use App\Observers\ProductObserver;

public function boot(): void
{
    Product::observe(ProductObserver::class);
}

方案2：模型内置事件

如果不想单独创建观察者，可以直接在Product模型中通过booted方法注册事件：

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Product extends Model
{
    protected static function booted(): void
    {
        static::saving(function (Product $product) {
            $product->restock = $product->stock == $product->min_stock ? 1 : 0;
        });
    }
}

方案3：直接在控制器中处理（不推荐）

如果只在当前的出库/入库场景处理，可以修改控制器代码，但后续新增库存修改场景时需要重复编写逻辑：

出库控制器修改：

foreach ($products as $product) {
    $productModel = Product::find($product->product_id);
    $newStock = $productModel->stock - $product->quantity;
    
    $productModel->update([
        'stock' => $newStock,
        'restock' => $newStock == $productModel->min_stock ? 1 : 0
    ]);
}

入库控制器修改：

foreach ($products as $product) {
    $productModel = Product::find($product->product_id);
    $newStock = $productModel->stock + $product->quantity;
    
    $productModel->update([
        'stock' => $newStock,
        'restock' => $newStock == $productModel->min_stock ? 1 : 0
    ]);
}

内容的提问来源于stack exchange，提问作者Yahya Setya Nurohman