Php 添加相同产品时增加$\会话中的数量值

我想通过单击“添加到购物车”来添加更多数量，但我的代码显示，它的最大数量为2

我的代码：

cart\u process.php

if(isset($_POST["product_code"]))
{
    foreach($_POST as $key => $value){
        $new_product[$key] = filter_var($value, FILTER_SANITIZE_STRING); //create a new product array 
    }

    //we need to get product name and price from database.
    $statement = $mysqli_conn->prepare("SELECT product_name, product_price FROM products_list WHERE product_code=? LIMIT 1");
    $statement->bind_param('s', $new_product['product_code']);
    $statement->execute();
    $statement->bind_result($product_name, $product_price);


    while($statement->fetch()){ 
        $new_product["product_name"] = $product_name; //fetch product name from database
        $new_product["product_price"] = $product_price;  //fetch product price from database
        $new_product["product_qty"] = 1;

        if(isset($_SESSION["products"])){  //if session var already exist
            if(isset($_SESSION["products"][$new_product['product_code']])) //check if item already exist in products array add more quantity +1
            {
                $_SESSION["products"][$new_product['product_code']] = $new_product["product_qty"]++;
            }           
        }

        $_SESSION["products"][$new_product['product_code']] = $new_product; //update products with new item array       //update products with new item array   

    }

    $total_items = count($_SESSION["products"]); //count total items
    die(json_encode(array('items'=>$total_items))); //output json 

}

第一次单击“添加到购物车”时的输出：

Array
(
    [products] => Array
        (
            [TSH1] => Array
                (
                    [product_color] => Red
                    [product_size] => M
                    [product_code] => TSH1
                    [product_name] => Cool T-shirt
                    [product_price] => 8.50
                    [product_qty] => 1
                )

        )

)

并在第二次单击时输出将同一产品再次添加到购物车：

[product_qty] => 2 // Quantity has been added when I click add the same product to cart

---

但当我再次单击“将同一产品添加到购物车”时，它不会添加更多数量。

取消设置[产品数量]并增加计数器。。。添加回会话数组

取消设置[产品数量]并增加计数器。。。添加回会话数组

unset（$\u会话[“产品”][$new\u产品['product\u数量]]）

对吗？

unset（$\u会话[“产品”][$new\u产品['product\u数量]]）

对吗？