Select specific values from json_decode in php - php

Question

I've stumbled on a problem that i think is a bit strange since i've followed other examples to the exact code but i still didn't get the same result.
Short summary
I'm developing a shopping application and i'm using a session for the cart. Since i want to have the possibility to remove items from the cart i am using some levels inside the JSON object of the session.
Cart summary
The cart is created on button click
$_SESSION['cart']["cartItems"][$product_id]=$cartProduct;
Where $cartProduct is an array() of items like the product_id, product_name, etc.
Where the cartlevel: $product_id is for the remove cart row function().
The cart is then shown in an angularJS application. I will pass the full view and just show the getCart section and the JSON response.
$json = json_encode($_SESSION['cart']['cartItems']);
echo($json);
The JSON echo is:
{"3":{"id":"3","name":"Bedrukte Jurk","price":25.99,"size":"M","quantity":"3","total_product_price":77.97},"2":{"id":"2","name":"Blouse","price":26.99,"size":"S","quantity":"3","total_product_price":80.97}}
The JSON is stripped by removing the ['cartItems'] value.
The $_SESSION['cart']'s original JSON object would be:
{"cartItems":{"3":{"id":"3","name":"Bedrukte Jurk","price":25.99,"size":"M","quantity":"3","total_product_price":77.97},"2":{"id":"2","name":"Blouse","price":26.99,"size":"S","quantity":"3","total_product_price":80.97}}}
{"cartItems":{"3":{"id":"3","name":"Bedrukte Jurk","price":25.99,"size":"M","quantity":"3","total_product_price":77.97},"2":{"id":"2","name":"Blouse","price":26.99,"size":"S","quantity":"3","total_product_price":80.97}}}
The question
So now i would like to select only the "name" ,"id" and other values seperatly since i have to write them to a database. it would be something like:
$json_test = json_decode($_SESSION['cart']['cartItems']['name']);
echo $json_test;
$product_name = $json_decode_name;
So at this moment my question really starts. i'm having one issue and one real question on how ould i achieve this (thinkin of using foreach()
So first my problem is that i can't, or i am not able to select the specific values from the json cart session. I've tried some things from the PHP docs and made a small comparison:
$json1 = '{"foo-bar": "123", "foo-bar2": "456"}';
echo($json1);
echo "<br>";
$obj = json_decode($json1);
print $obj->{'foo-bar2'}; // 456
echo "<br>";
$json_decode = json_decode($_SESSION['cart']['cartItems']['3']);
print $json_decode->{'name'};
echo "<br>";
var_dump(json_decode($_SESSION['cart']['cartItems']['3'], true));
echo "<br>";
$json = json_encode($_SESSION['cart']);
echo($json);
The $json1 is working but i can't quite get my own version working.
Some extra tips?
The second thing is then pushing it to the database. I was thinking about: when achieving the name / names from the JSON string i would use a foreach() statement. Something in the area of:
$cart_product_name = $json_decoded_name
foreach ($cart_product_name as $product_name) {
insert_Query
}
And repeat this for the id's, quantity's, etc.
If the question isn't clear please let me know in the comments and i'll edit it.
As always, Thanks in advance!