Php 如何从不同的表将多个项目添加到一个购物车中

我想添加多个项目到一个购物车，从两个不同的表，如自定义产品和产品。我可以将产品添加到购物车，但在将自定义产品添加到购物车时遇到问题。我希望你们理解我的问题，所以请指导我如何从两个不同的表将多个项目添加到一个购物车中

产品

• 身份证
• 名字
• 描述
• 供应商id

定制产品

• 身份证
• 风味
• 形状
• 描述
• 供应商id

推车

• 身份证
• 客户识别码
• 产品标识
• 客户产品标识

函数getCart Item

          $allCartItems = Cart::where([
                    'customer_id' => $customerId
                ])->get()->map(function ($instance) {
                    $product = Product::find($instance->product_id);
                    $instance->product = $product;
                    $instance->quantity = 1;
                    return $instance;
                })->toArray();
    
                $subTotal = array_reduce($allCartItems, function ($acc, $instance) {
                    return $acc + $instance['product']['product_price'];
                }, 0);
    
                $mergedArr = [];
    
                foreach ($allCartItems as $key => $instance) {
                    $filter = function ($item) use ($instance) {
                        return $item['product_id'] == $instance['product_id'];
                    };
    
                    $existingItem = array_filter($mergedArr, $filter);
    
                    if ($existingItem) {
                        $mergedArr[sizeof($mergedArr) - 1]['quantity'] = $mergedArr[sizeof($mergedArr) - 1]['quantity'] + 1;
                    } else {
                        array_push($mergedArr, $instance);
                    }
                }
    
                $payload = (object)[];
                $payload->products = $mergedArr;
                $payload->subTotal = $subTotal;
    
                return  $payload;

        

函数AddtoCart

       function($Request request){
                   $customerId = $request->customer_id;
            $productId = $request->product_id;
    
            $product = Product::find($productId);
            $existingCart = Cart::where(['customer_id' => $customerId])->first();
    
            if ($existingCart) {
                $vendorId = $existingCart->product->vendor->id;
    
                if ($product->vendor->id !== $vendorId) {
                    throw new Exception('You cannot add product from different vendor.');
                }
            }
    
            Cart::create([
                'product_id' => $productId,
                'customer_id' => $customerId
            ]);
    
            $payload = getCartItem($customerId);
    
               $customerId = $request->customer_id;
            $productId = $request->product_id;
    
            $product = Product::find($productId);
            $existingCart = Cart::where(['customer_id' => $customerId])->first();
    
            if ($existingCart) {
                $vendorId = $existingCart->product->vendor->id;
    
                if ($product->vendor->id !== $vendorId) {
                    throw new Exception('You cannot add product from different vendor.');
                }
            }
    
            Cart::create([
                'product_id' => $productId,
                'customer_id' => $customerId
            ]);
    
            $payload = getCartItem($customerId);
    
            return response()->json([
                'success' => true,
                'message' => 'success!',
                'payload' => $payload
            ]);
        }

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你的错误是什么？