Problem With Locating Existing Items In Cart, Keeps Adding Another Row

[jsmith1981]

I have some weird problem here,

 

The code is:

if($cart_count == 0)
{

    $_SESSION['cart'][] = $tmp_product;

} else if($cart_count > 0) {

    // if the array has anything in it:

    for($i=0; $i<$cart_count; $i++)
    { 
        // loop through the array rows:

        // if the id of the product already is in there then add to it:
        if($_SESSION['cart'][$i]['id'] === $tmp_product['id'])
        {
            // adds to the already there qty: preincrement actually I think
            $_SESSION['cart'][$i]['qty'] += $tmp_product['qty'];                

        } else {

            // otherwise add to it regardless of the conditional kind of...
            $_SESSION['cart'][] = $tmp_product;

        }
    }
}

The problem I am having is when I add the same product again it updates the qty that's fine works perfectly but if I was to go and add another product say product 2 as opposed to product 1 (that was added just prior) it keeps adding rows to the array, what's wrong with my logic to suggest it does this?

 

It must be something pretty obvious I am missing I just can't see it.

 

I appreciate anyone's help,

Jeremy.

[falkencreative]

Are you following any specific tutorials? Or is this your own code?

 

The first thing I notice is this section:

if($_SESSION['cart'][$i]['id'] === $tmp_product['id'])
{
// adds to the already there qty: preincrement actually I think
$_SESSION['cart'][$i]['qty'] += $tmp_product['qty']; 
}

I'm not sure how the use of $i there makes sense... you'll just end up with random numbers (from the for loop) with no specific meaning in your array. Are you sure that isn't supposed to be $id instead? Since that would make a lot more sense.

[jsmith1981]

			// we need all the details of the product so we can add it to the cart (the needed data that means)
			$sql = sprintf("SELECT id, name, price FROM products WHERE id = '%d'", $prodid);
			
			// query the products table:
			$result = mysql_query($sql);
			
			// if no result send the user back the the home page:
			if(!$result)
			{
			
				header("Location: index.php");
			
			// else construct the ability to add the product to the cart, if the result is true and counts for 1 row:
			} else if ($result && mysql_num_rows($result) == 1) {
				
				// get the one row:
				$row = mysql_fetch_row($result);
				
				$tmp_product = array('id'=>$row[0],
						'name'=>$row[1],
						'price'=>$row[2],
						'qty'=>$_POST['qty']);
			}
			
			$cart_count = count($_SESSION['cart']);
			
			if($cart_count == 0)
			{
				
				$_SESSION['cart'][] = $tmp_product;
				
			} else if($cart_count > 0) {
				
				// if the array has anything in it:
				
				for($i=0; $i<$cart_count; $i++)
				{ // loop through the array rows:
					
					// if the id of the product already is in there then add to it:
					if($tmp_product['id'] == $_SESSION['cart'][$i]['id'])
					{
						// adds to the already there qty: preincrement actually I think
						$_SESSION['cart'][$i]['qty'] += $tmp_product['qty'];
					
					} else if ($tmp_product['id'] != $_SESSION['cart'][$i]['id']) {
						
						// otherwise add to it regardless of the conditional kind of...
						$_SESSION['cart'][] = $tmp_product;
						
					}
				}
			} // end of adding product

That's the whole process for the add to cart part of the code I wrote, it's really kind of half going off what I can remember (or lack of lol) what's in 2 different books as a kind of inspiration.

 

I appreciate your next reply,

Jeremy.

[falkencreative]

Probably the first step for me, if I were handling this, would be to display some debugging messages -- try echoing out the different variables, specifically the $tmp_product array and the cart Session variable, and make sure you're dealing with the data you expect.

[jsmith1981]

Yea I did that and sadly they're both comparing so would return to be true, so there's nothing wrong within itself just it's not behaving the way I'd want it to.

 

I actually played around with another example another developer was using and came up with this that works:

		case 'add':
			
			// we need all the details of the product so we can add it to the cart (the needed data that means)
			$sql = sprintf("SELECT id, name, price FROM products WHERE id = '%d'", $prodid);
			
			// query the products table:
			$result = mysql_query($sql);
			
			// if no result send the user back the the home page:
			if(!$result)
			{
			
				header("Location: index.php");
			
			// else construct the ability to add the product to the cart, if the result is true and counts for 1 row:
			} else if ($result && mysql_num_rows($result) > 0) {
				
				// get the one row:
				$row = mysql_fetch_row($result);
				
				$tmp_product = array('id'=>$row[0],
						'name'=>$row[1],
						'price'=>$row[2],
						'qty'=>$_POST['qty']);
			}
			
			$cart_count = count($_SESSION['cart']);
			
			if($cart_count === 0)
			{
				
				$_SESSION['cart'][] = $tmp_product;
				// this is fine!
				
			} else  {
				
				$already_in_cart = false;
				
				for($i=0; $i<$cart_count; $i++)
				{ // loop through the array rows:
					
					// if the id of the product already is in there then add to it:
					if($_SESSION['cart'][$i]['id'] === $tmp_product['id'])
					{
						
						$_SESSION['cart'][$i]['qty'] = $_SESSION['cart'][$i]['qty'] + $tmp_product['qty'];
						
						$already_in_cart = true;
						break;
					  
					}
				}
				
				if($already_in_cart === false)
				{
					$_SESSION['cart'][] = $tmp_product;
				}
				
			} // end of adding product
		break;

Thank you so much for your help Ben.