|string> */ public function rules(): array { return [ 'external_order_id' => 'required|string', 'machine_id' => 'nullable|string', 'warehouse' => 'nullable|string', 'warehouse_id' => 'nullable|integer', 'payment_method' => 'nullable|string|in:cash,electronic,line_pay,other', 'sold_at' => 'nullable|date', 'items' => 'required|array|min:1', 'items.*.product_code' => 'required|string', // 使用 ERP 商品代碼 'items.*.qty' => 'required|numeric|min:0.0001', 'items.*.price' => 'required|numeric|min:0', ]; } }