PHP | empty function can work with object properties ? | Simple issue - php

Question

I am creating a kind of shopping cart for a very specific purpose, and I have create two basic classes. The one class is made to describe a product in the cart, and the other class is the cart.
My CartItem class looks like that:
class CartItem
{
private $id = null; // This is the product id
private $qty = 0; // This is the product Quantity
private $price = 0; // This is the product price
private $name = ''; // This is the product name
private $options = array(); // This array contains the product options
private $rowid = null; // This is the product id in the cart
private $subtotal = 0; // This is the product sub total
public function __construct(
$id = null,
$qty = null,
$price = null,
$name = null,
$options = array()
)
{
$this->id = $id;
$this->qty = (float)$qty;
$this->price = (float)$price;
$this->name = $name;
$this->options = $options;
}
public function __get($name)
{
return $this->{$name};
}
...
public function setQty($qty = 0)
{
$this->qty = (float)$qty;
return $this->qty;
}
...
}
and my Cart class is the following:
class Cart
{
protected $cart_contents = array();
protected $cart = null;
protected function __construct()
{
$this->cart = new SessionContainer('cart_contents');
$this->cart_contents = $this->cart->offsetGet('contents');
if(count($this->cart_contents) <= 2)
{
$this->cart_contents = array(
'cart_total' => 0,
'total_items' => 0
);
}
}
public function insert(CartItem $item)
{
$save_cart = false;
if(($rowid = $this->_insert($item)))
{
$save_cart = true;
}
if($save_cart === true)
{
$this->_save_cart();
return isset($rowid) ? $rowid : true;
}
return false;
}
protected function _insert(CDOCartItem $item)
{
if($item->qty == 0)
{
return false;
}
if(is_array($item->options) && count($item->options) > 0)
{
$rowid = md5($item->id . serialize($item->options));
}
else
{
$rowid = md5($item->id);
}
$old_quantity = isset($this->cart_contents[$rowid]->qty) ? $this->cart_contents[$rowid]->qty : 0;
$item->setRowId($rowid);
$item->setQty($item->qty + $old_quantity);
$this->cart_contents[$rowid] = $item;
return $rowid;
}
public function update(CDOCartItem $item)
{
$save_cart = false;
if($this->_update($item) === true)
{
$save_cart = true;
}
if($save_cart === true)
{
$this->_save_cart();
return true;
}
return false;
}
protected function _update(CartItem $item)
{
echo "Is this empty : " . empty($item->qty) . " : " . $item->qty;
if(empty($item->qty) || empty($item->rowid) || !isset($this->cart_contents[$item->rowid]))
{
return false;
}
$item->setQty((float)$item->qty);
if($item->qty <= 0)
{
unset($this->cart_contents[$item->rowid]);
}
else
{
$this->cart_contents[$item->rowid]->qty = $item->qty;
}
return true;
}
}
Then I try to play with this structure:
$item = new CartItem('SKU-12321', 12, 47.82, 'Name');
$cart = Cart::Instance(); // I have apply the singleton patternt in my local files
$itemRID = $cart->insert($item);
$newItem = $cart->get_item($itemRID); // This method return the object based on ID and 100% works in my code
$newItem->setQty(25);
$cart->update($newItem);
But the problem is that I am getting the following result:
Is it empty : 1 : 25
The above line is printed in the Cart Class in the update method.
As you can see, I am testing if the $item->qty is empty, and the test returns true, and in the same value I am echoing the current item quanity that it is 25 so, the actual property it is not empty.
Am I doing something wrong ? In PHP Documentation they are describing that the function empty can be used to test for empty or null values in variables, but I am not sure if that works in properties.
Can somebody to help me please ?

Answer 1

I think the problem comes from your CartItem::__get(). I explain: $qty is private, so a empty($item->qty) returns true because it is not accessible outside the element, but when you access it with just $item->qty, the variable will be considered as unexisting (because it is private) so the __get() method will be called and will return the right value because you access it within the class.