PHP session sum cart quantity even different product id - php

Question

I have session to add product cart.
$getProductID = mysqli_real_escape_string($con, $_POST['productID']);
$getQuantity = mysqli_real_escape_string($con, $_POST['quantity']);
foreach($_POST as $key => $value)
{
$new_product[$key] = filter_var($value, FILTER_SANITIZE_STRING);
}
$qProduct = mysqli_query($con, "SELECT * FROM tb_product WHERE productid = '" . $getProductID . "'");
$dProduct = mysqli_fetch_array($qProduct);
$product_id = $dProduct['productid'];
$product_name = $dProduct['product_name'];
$product_price = $dProduct['product_price'];
$new_product["productid"] = $product_id;
$new_product["product_name"] = $product_name;
$new_product["product_price"] = $product_price;
$new_product["quantity"] = $getQuantity;
if(isset($_SESSION["products"]))
{
if(isset($_SESSION["products"][$new_product['productid']]))
{
unset($_SESSION["products"][$new_product['productid']]);
}
}
$_SESSION["products"][$new_product['productid']] = $new_product;
$total_items = count($_SESSION["products"]);
foreach($_SESSION["products"] as $product)
{
$product_quantity = $product["quantity"];
}
die(json_encode(array('items'=>$product_quantity)));
Then now I want to get session of product quantity
foreach($_SESSION["products"] as $product)
{
echo $product_quantity = $product["quantity"];
}
I can get the quantity as well, until I try to add another product cart it's not sum the quantity.
Example, on Product1 I add to cart 5pcs (I can see the quantity is 5)
and then I add Product2 to cart 3pc (It show me 53 that should be 8).
My question, how to sum the quantity even Product ID is different?

Answer 1

Change your loop as below, Sum inside loop and move echo outside of loop.
$product_quantity = 0;
foreach($_SESSION["products"] as $product)
{
$product_quantity += $product["quantity"];
}
echo $product_quantity;

Answer 2

I think because your coding have something wrong
//Incorrect
foreach($_SESSION["products"] as $product)
{
echo $product_quantity = $product["quantity"];
}
//first loop echo-ed 5
//second loop echo-ed 3
//so it show 53
//Correct
$product_quantity = 0;
foreach($_SESSION["products"] as $product)
{
$product_quantity += $product["quantity"];
}
echo $product_quantity;