[problem - Shopping Cart tutorial, video 7]

here's the link code i'm using:

 

Add to Cart

 

it's very weird and hard to explain...the two browsers (ff & chrome) were seemingly refreshing the page when i clicked the link, thus adding another product in the page transition, giving me 1 product in the cart and 2 in the source code...

 

ie6 doesn't do this...and i've been conditioned to believe if ie6 gets something right, it's really wrong...

 

i also put the project code on my server, only changing the '<?=' to '<?php echo' and got the same weird browser behavior...and, i've been over the code several times and can't see an error anywhere...

 

so i gave up and used the button...and it works...i don't know why...

[problem - Shopping Cart tutorial, video 7]

wahoo!...i've finally fixed this by using a button with addToCart.php as the action:

 

 

but i have no idea why it works and the link doesn't...

[Shopping cart tutorial quantity won't go up start session problem]

i uploaded my 'magic cart' to my web server for further testing and ran into this 'headers already sent' issue myself...

 

after following falkencreative's solutions the issue didn't resolve...then i found this: http://www.phpbuilder.com/board/showthread.php?t=10310794 ...post #8 was what caused my headers to be sent...there are other ideas there too...

[Shopping cart tutorial quantity won't go up start session problem]

i'm still a bit new to php, but i've heard that 'headers already sent' is usually a white space problem...try putting 'session_start();' on the same line as '/** FUNCTIONS **/' and return directly after the slash...

[problem - Shopping Cart tutorial, video 7]

to further complicate things, the problem behavior occurs in both firefox 3.0 and google chrome; but in ie6 (i'm sorry), the shopping cart code performs perfectly, as expected...i can add an item, go back and add more, etc and the source codes is correct...

 

???

[problem - Shopping Cart tutorial, video 7]

Update: my shopping cart is 'magical' ...this situation is truly bizarre!

 

after staring at this code for another day, i've noticed that when i click on the 'addToCart' link, the addToCart page displays 1 item in the quantity with the correct amount, shipping, and total; however, on viewing the source code i see this:

 

>
</pre>
<table>Product IDQuantityAmountTULIPCHOC3$74.97Shipping:$32.97Total:$107.94</table>

 

it's good math, but not a practical application ...thoughts?

[problem - Shopping Cart tutorial, video 7]

from ShoppingCart.php:

 

<?php
class ShoppingCart {
   protected $items = array();

   public function AddItem($product_id) {
       if(array_key_exists($product_id, $this->items)) {
           $this->items[$product_id] = $this->items[$product_id] + 1;
       }
       else {
           $this->items[$product_id] = 1;
       }
   }

   public function GetItemCost($product_id) {
       $cost_string = get_item_cost($product_id);
       $cost_float = "$cost_string" + 0;

       return $cost_float * $this->GetItemQuantity($product_id);
   }

   public function GetItemShippingCost($product_id) {
       return $this->GetItemQuantity($product_id) * $this->getShippingCostFor(get_item_cost($product_id));
   }

   private function getShippingCostFor($price) {
       if ($price < 10) {
           return 1.99;
       }
       elseif ($price < 50) {
           return 10.99;
       }
       else {
           return 34.99;
       }
   }

   public function GetItems() {
       return array_keys($this->items);
   }

   public function GetItemQuantity($product_id) {
       return intval($this->items[$product_id]);
   }

   public function EmptyCart() {
       $this->items = array();
   }
}
?>

 

and functions.php:

<?php
// DEFINE GLOBALS

define ('STORE_XML_FILE', '../catalog.xml');

// DEFINE REFERENCES

require_once ('templates.php');

require_once ('../classes/ShoppingCart.php');

// FUNCTIONS
session_start();

function get_xml_catalog() {
   return new SimpleXMLElement(file_get_contents(STORE_XML_FILE));
}

function get_item_cost($product_id) {
   foreach(get_xml_catalog() as $product) {
       if ($product_id == $product->id) {
           return $product->price;
       }
   }
   throw new Exception('item not found: ' . $product_id);
}

function product_exists($product_id) {
   foreach(get_xml_catalog() as $product) {
       if ($product->id == $product_id)
           return true;
   }
   return false;
}

function get_shopping_cart() {
   if (!isset($_SESSION['cart'])){
       return new ShoppingCart();
   }
   else
       return unserialize($_SESSION['cart']);
}

function set_shopping_cart($cart) {
   $_SESSION['cart'] = serialize($cart);
}
?>

[problem - Shopping Cart tutorial, video 7]

i'm working my way thru the shopping cart tutorial...in video 7, 12:13 minutes in...i've just completed the code for $quantity:

 

><?php
   $product_id = $_REQUEST['id'];

   if (product_exists($product_id)) {
       $shopping_cart->AddItem($product_id);
   }
?>

</pre>
<table>Product IDQuantityAmount
           $product_id

           $quantity

           $ amount
</table>
<br><br><?php set_shopping_cart($shopping_cart);<br><br

 

in the video, when he refreshes the page, the item quantity goes up 1 as expected...when i refresh my page, the item quantity goes up by 2 each time...not good...

 

i've compared my code with the code base and don't see an error...in my first attempt, i continued on with the videos, hoping the issue would resolve, but it didn't...so, i scrapped that code and started again from scratch, with the same result...checked the code again and i'm still not seeing an error...any thoughts as to what might be the cause?