strange thing about $_POST array when it's passed another page

[Duke555]

i have noticed a strage thing about a $POST array and i was wondering if someone could help me understand how $POST works better.
in the form below with use 'post' in order access default values (stored by $temp_number) product quantities one would have to use:

[INDENT]$_POST['cart']["$name"][/INDENT]

and it makes sense since this form has a 'name="cart"'

However, once a user cick on SUBMIT and he is taken to my_cart.php

than to access quantities of goods from the user's input one has to use:

[INDENT]$SESSION['cart'][$name]['qty']=(int)$POST["$name"];[/INDENT]

which means one cannot access quantities of products input by the user
via $_POST['cart']["$name"]

why is this like that?
should not the $_POST array be the same when it is passed on to another page?

than you 🙂

<form action="my_cart.php" name="cart" method="post">

.....
.....
		<td align="left"><input type="text" size="3" name="<?echo $name;?>" value='<?$temp_number = 0; echo $_POST['cart']["$name"]=$temp_number;?>' /></td>
			<td align="right"><? echo number_format($grand_total, 2);?></td>
		</tr>
		<? 
		$_SESSION['cart'][$name]['qty']=(int)$_POST['cart']["$name"];
	}

...[/CODE]

[ixalmida]

I'm not sure I understand what you are trying to do, but let's just check a few things. Firstly, are you aware that a form field name needs brackets next to it to be passed as an array? So this form field will POST as an array:

<input type="checkbox" name="selection[]" value="1">
<input type="checkbox" name="selection[]" value="2">
etc...

To access the array on the next page, you just use the variable $_POST['selection'] - there won't be any named indexes in such an array. You would be best off simply using a foreach() statement:

foreach($_POST['selection'] as $value)
  {
  // Do something with the selection.
  }

If I understand your code right, you are trying to access a form field through the form name - this is not necessary. Even if you have multiple forms on a page, it will only post the data submitted by the post action of the current form (as in, whichever "Submit" button the user clicks).

[Duke555]

thank you for your reply 🙂
i was not sure if we understoof each other correctly. for this reason i am posting a complete code below.
what ahppens in this code is like this:
SESSION acts as a copy of another array that in turn was used as a very simple database to store items and etc.
POST on the other hand is used to store quantities of items had the user decided to buy any of them.

thanks again!

	<form action="my_cart.php" name="cart" method="post">
	<?
	//traversing outer array in this loop
	//'name' is the 'key' and 'description' is the 'value' of this outer array
	while (list($name, $description) = each($product))
	{
		//calculate shipping charge in dollars
		$shipping = $description["Shipping"] * $description["Price"];
		//calculating grand total of an item's 'price' and 'shipping' which are stored in the inner
		//array and are pointed by the keys 'price' and 'shipping' respectively
		// NOTE: both $total and $shipping do NOT include TAX
		$total = $description["Price"] + $shipping;
		echo '<br>$description["Price"] <br>'. $description["Price"];
		echo '<br>$description["Shipping"] <br>'. $description["Shipping"];
	?>
	<tr>
		<td align="left"><? echo $name;?></td>
		<td align="left"><? echo number_format($description["Price"], 2);?></td>
		<td align="left"><? echo number_format($shipping, 2); ?></td>
		<td align="left"><input type="text" size="3" name="<?echo "$name";?>" value='<?$temp_number = 0; echo $_POST['cart']["$name"]=$temp_number;?>' /></td>
			<td align="right"><? echo number_format($total, 2);?></td>
		</tr>
		<? 
		//for each product in SESSION[cart] set quantity to the default value ($temp_number == 0 therefore default value is 0)
		//use casting (int) to prevent hacking attacks/ misuse of the site i.e. convert all the input values into numbers regardless of the input
		$_SESSION['cart'][$name]['qty']=(int)$_POST['cart'][$name];
		echo "<br>\$name ".$name."<br>";
		echo "<br>'\$name' ".$name."<br>";		
	}
	echo "<br>printing _POST<br>";
	print_r($_POST);
	echo "<br>printing _SESSION<br>";
	print_r($_SESSION);	
	echo "<br>";
		// Print the footer, close the table, and the form:
		?><tr>
			<td colspan="4" align="right"><b>Total:</b></td>
			<td align="center">TEST</td>
		</tr>	
		<tr>
			<td colspan="6" align="center">TEST</td>
		</tr>
		</table><div align="center"><input type=submit value="SUBMIT"></div>
</form>

[faifas]

Duke,

you do not need to access $_POST variables by form name.

Instead, elements in your form has names, which are used to access them. If you still want to use a name for form go ahead, but do not try to access elements that way.

So, for example form's

<form name="cart" action="cart.php">
<input type="text" name="item" />
<input type="submit" />
</form>

data would be accessed with:

$_POST['item'];

to get a better understanding of names, try pasting this code into your form's action file:

<?php
echo '<pre>';
print_r($_POST);
echo '</pre>';
die;
?>

then submit the form and see what happens.

Hope this helps!

[ixalmida]

Maybe I'm thick, but I still don't understand your code. I think you're making the whole process overly complicated. Let's say you want to store your cart in a single session variable that you can unset once you are done with it. Assuming a single user can only have one cart, your array might be $_SESSION['cart'].

So now let's say the user adds an item to their cart. I can only think of 3 pieces of information you'd need for an item (assuming the rest is stored in your database): item number, quantity, and maybe coupon code. So now you've got: $SESSION['cart']['item1']['item_no'], $SESSION['cart']['item1']['quantity'], and $_SESSION['cart']['item1']['discount'].

So you've got the SESSION array, but you're only dealing with a single cart. Then you've got a number of items in a cart which may grow, but will only ever have 3 pieces of information associated with them.

Now you need to display your cart:

$items = $_SESSION['cart'];
foreach($items as $item)
  {
  // Get item info...
  $query = "SELECT description, price FROM Items WHERE item_no = ".$item['item_no'];
  $result = mysql_query($query, $link);
  $row = mysql_fetch_assoc($result);
  extract($row);

  // Calculate discounts...
  if($item['discount'] != 0)
    $price = $price - $item['discount'];

  // Calulate line total...
  $line_tot = $price * $item['quantity'];

  // Display line item...
  echo $item['item_no']." - ".$description." - ".$price." - ".$item['quantity'].
    " - ".$line_tot."<br>";
  }

Obviously, I'm keeping it simple here. You'd want to add a table and fields for changing the quantity before checkout.

[Duke555]

thank you i did work it out in the end 🙂

my only question that still remains is why i may access $_POST variables via form name on my initial page. but i cannot do so on my_cart.php which where this form is being passed to.

thank you

P.S. ixalmida: i know that had i used $-SESSION it would have worked like you are saying. I chose to use $POST in the beginning and then due to the time constraints
stuck with POST 🙂

[ixalmida]

I get that. I sometimes look back at my early code and wonder what I was thinking but I rarely have time to fix those mistakes.