Selecting and using JSON array values - php

Question

I'm currently working on a shopping application but i stumbled upon a problem. The problem is that i can't select the JSON values from my "shopping cart". See the following code and description.
So by using add to cart buttons and such i'm creating the shopping cart. The shopping cart is actually a JSON object. An example of the cart:
{"cartItems":{"2":{"id":"2","name":"Blouse","price":26.99,"size":"M","quantity":"3","total_product_price":80.97},"5":{"id":"5","name":"Bedrukte Zomerjurk","price":30.5,"size":"L","quantity":"4","total_product_price":122}},"totalPrice":202.97,"totalItems":2,"customerSelect":{"id":"1","firstname":"John","lastname":"TestStefans"}}
As you can see the design of my JSON cart is:
cart:{"cartItems":{"id":{ product information }}}
The problem now is trying to select the values like the "name" and "price". This due to the "id"{ segment. But i need that piece for removing one item by id from the cart.
So my question is:
How would i be able to select all the product information and create an foreach for placing the information in the database / email template. I've been trying this but this only gave me the first product:
$cart_encode = json_encode($_SESSION['cart']['cartItems']);
$cartDecode = json_decode($cart_encode);
// Adding the product items
foreach ($cartDecode as $key => $cartItem) {
$resource->associations->cart_rows->cart_row->id_product = $cartItem->{"id"};
$resource->associations->cart_rows->cart_row->id_product_attribute = 1;
$resource->associations->cart_rows->cart_row->id_address_delivery = 1;
$resource->associations->cart_rows->cart_row->quantity = $cartItem->{"quantity"};
}
Take note that i'm using XML for database input. For the email template i've tried:
$testName = $_SESSION['cart']['cartItems']['name'];
$testPrice = $_SESSION['cart']['cartItems']['price'];
$testQuantity = $_SESSION['cart']['cartItems']['quantity'];
$testTotal = $_SESSION['cart']['cartItems']['total_product_price'];
$testProduct = array(
"Name:" => $testName,
"Price:" => $testPrice,
"Quantity" => $testQuantity,
"Total" => $testTotal
);
Iknow that the id number is missing but i cant dynamicly avoid that layer.
I hope that my question is clear
As always. Thanks in advance!