Removing array item from session in CakePHP - arrays

Question

I've added an array (shopping cart) into session. Now to remove an item from cart, I tried this logic. The cart is working fine and I can see all the items from the cart on my page. The removing logic is not giving me any error but also not removing the item from session.
What am I doing wrong?
function addToCart(){
$this->layout = false;
$this->render(false);
$cart = array();
$tempcart = unserialize($this->Session->read("cart"));
if(isset($tempcart)){
$cart = $tempcart;
}
$productId = $this->request->data("id");
if(!$this->existsInCart($cart, $productId)){
$cart[] = array("productId" => $productId, "createdAt" => date());
$this->Session->write("cart", serialize($cart));
echo "added";
}
else
echo "duplicate";
}
function removeFromCart(){
$this->layout = false;
$this->render(false);
$cart = array();
$tempcart = unserialize($this->Session->read("cart"));
if(isset($tempcart)){
$cart = $tempcart;
}
$productId = $this->request->data("productId");
for($i=0;$i<count($cart);$i++){
$cartItem = $cart[$i]; // an array
if($cartItem["productId"]==$productId)
unset($cart[$i]);
}
$this->Session->write("cart", serialize($cart));
echo "removed";
}

Answer 1

You were not updating the session with the correct value
function removeFromCart() {
$this->layout = false;
$this->render(false);
$productId = $this->request->data("productId");
// make sure this is the value you need
debug($productId);
$tempCart = unserialize($this->Session->read("cart"));
if (!empty($tempCart)) {
for ($i=0; $i<count($tempCart); $i++) {
if ($tempCart[$i]["productId"] == $productId) {
unset($tempCart[$i]);
}
}
$this->Session->write("cart", serialize($tempCart));
}
echo "removed";
}

Answer 2

$productId = $this->request->data("productId");
Are you sure you want to write "productId" instead of "id"?
You seem to have sent "id" in the request during add-to-cart, possibly you are doing the same while deleting.
Also, you have your cart saved in $cart, so you need to serialize $cart and not $newcart.
So your remove from cart code becomes:
function removeFromCart(){
$this->layout = false;
$this->render(false);
$cart = array();
$tempcart = unserialize($this->Session->read("cart"));
if(isset($tempcart)){
$cart = $tempcart;
}
$productId = $this->request->data("id");
for($i=0;$i<count($cart);$i++){
$cartItem = $cart[$i]; // an array
if($cartItem["productId"]==$productId)
unset($cart[$i]);
}
$this->Session->write("cart", serialize($cart));
echo "removed";
}

Answer 3

why you aren't using just delete() function of session component ?
$this->Session->delete('cart');