[RESOLVED] Array checking problem.

[webdevmydnac]

What im trying to do is add items to a cart. Checking if the key(product id) already exists in the array.

Where im getting stuck is when i check to see if the key exists.
if it does exist i want to add the supplied quantity of items to that product key. instead of doing this it just overwrites the key and values losing the old quantities.

Any ideas?

	public function WriteToCart(){		
		$prdct_id = $_POST['prdct_id'];
		$qty = $_POST['qty'];
		$this->cartArray=$_SESSION['cart.items'];
		foreach ($this->cartArray as $key => $value){
			$prdctid = $key;
			$prdctqty = $value;
			if (array_key_exists($prdct_id, $this->cartArray)) {
				$new_qty = $prdctqty + $qty;
				$this->cartArray[$prdct_id]=$new_qty;
				$_SESSION['cart.items']=$this->cartArray;
			}
		}
		$this->cartArray[$prdct_id]=$qty;
		$_SESSION['cart.items']=$this->cartArray;

}	

[igorlopez]

I have not started with OO and do not know if that is the reason it does not work for you.
The check in part is simply this:

if(array_key_exists($prdct_id, $this->cartArray))
{
	// This product item already exist, update cart
	$this->cartArray[$prdct_id] += $qty;
}
else
{
	// just add this new item to cart
	$this->cartArray[$prdct_id] = $qty;
}

My simple test code (without using session data as global container or POST data) works with the above construction.

function checkInItem(&$cart, $id, $qty)
{
	if(array_key_exists($id, $cart))
	{
		// This product item already exist, update cart
		$cart[$id] += $qty;
	}
	else
	{
		// just add this new item to cart
		$cart[$id] = $qty;
	}	
}
// current cart items
$cartItems = array('prodId_1' => 2, 'prodId_5' => 1, 'prodID_17' => 12);
// check in data for item 1
$item1_id = 'prodId_7';
$item1_qty = 1;
// check in data from item 2
$item2_id = 'prodId_5';
$item2_qty = 3;

// Look at the cart before
echo "Cart contains initially: <br>";
print_r($cartItems);
echo "<br>";

echo "<br>Adding item1 with product ID = $item1_id and qty = $item1_qty<br>";
// check in item1 into cart
checkInItem($cartItems, $item1_id, $item1_qty);

echo "Adding item2 with product ID = $item2_id and qty = $item2_qty<br>";
// check in item2 into cart
checkInItem($cartItems, $item2_id, $item2_qty);

// Look at the cart after items added
echo "<br>Cart contains after the items were added: <br>";
print_r($cartItems);
echo "<br><br>";

Output is

Cart contains initially:
Array ( [prodId_1] => 2 [prodId_5] => 1 [prodID_17] => 12 )

Adding item1 with product ID = prodId_7 and qty = 1
Adding item2 with product ID = prodId_5 and qty = 3

Cart contains after the items were added:
Array ( [prodId_1] => 2 [prodId_5] => 4 [prodID_17] => 12 [prodId_7] => 1 )

[webdevmydnac]

thanks for the expedient answer.
it helped me along nicely. below is my solution.

class cart{
	public function WriteToCart(){		
		if (isset($_POST['prdct_id']) && is_numeric($_POST['prdct_id'])){
			$prdct_id = $_POST['prdct_id'];
			$qty = $_POST['qty'];
				if (isset($_SESSION['cart.items'][$prdct_id])){
					$_SESSION['cart.items'][$prdct_id]['qty'] += $qty;
				}
		else {
			$qty = $_POST['qty'];
			$_SESSION['cart.items'][$prdct_id] = array('qty' => $qty);
		}
		}
	}
	public function RemoveFromCart(){

}

}

Now on to removing items, and totaling price.
Then the really fun stuff begins... Sending it through to paypal...