RE: [PHP] headers already sent and cookie problem

[frederik feys]

Hi Mike, hi all,

I solved this nasty one! Happy. Your analysis is totally correct, Mike.
Every visitor who puts an item in cart for the first time will get a
cookie and... receives the error on his screen. And I, ... I didn't have
this error message! 
What did it for me was:
<?
session_start();

include_once("../Connections/Aurelis.php"); 
include_once($DOCUMENT_ROOT . "/includes/functions/get_label.php"); 
include_once($DOCUMENT_ROOT . "/includes/functions/countries.php");  
include_once($DOCUMENT_ROOT .
"/store/includes/functions/calculate_shipping.php"); 
include_once($DOCUMENT_ROOT .
"/store/includes/functions/get_cartID.php");

$cookie = GetCartId();

--> so , i just called the function and assigned it to a variable and...
gone with the wind!

Thanks again Mike!

Regards
Fred



-----Original Message-----
From: Ford, Mike [LSS] [mailto:[EMAIL PROTECTED] 
Sent: vrijdag 18 juli 2003 18:20
To: 'frederik feys '; '[EMAIL PROTECTED] '
Subject: RE: [PHP] headers already sent and cookie problem


-----Original Message-----
From: frederik feys
To: 'Ford, Mike               [LSS]'; [EMAIL PROTECTED]

Here's the URL:
http://www.aurelis.org/store/cart.txt
and the get_cartID:
http://www.aurelis.org/store/includes/functions/get_cartID.txt

--------------------------

I've only had time for a quick look, but I think I have an inkling of
where
your problem might be.

It all seems to lie with the way you've implemented GetCartId() -- and
the
problem will only show up any time the cartId cookie is not already set.
Basically, if the cookie is not set, GetCartId() generates a new ID and
sets
the cookie -- but this requires sending a header, and you can't do this
once
you've started output of the real page.  So you must make you first call
to
GetCartId() *before* you send any output.  Now, if we look at this
fragment
of code from /store/cart.txt:

  function ShowCart($lang)
  {
  global
$connection,$lang_dir,$DOCUMENT_ROOT,$page_theme,$country_iso_code,$srch
_ter
m;

  /* ob_start(); //start buffering output */

  $page_title=get_label(194,$lang,$connection);
  $page_tab=3;
  include_once($DOCUMENT_ROOT . "/header_aurelis.php"); 
 

  $country_iso_code = $_GET[country_iso_code]; 

  if($lang=="EN"){
        $currency_symbol = "$ ";
        }
  else{ 
        $currency_symbol = "&euro; "; 
        }
        
  $totalCost = 0;
  $show_cart = @mysql_query(("select * from cart inner join items on
cart.itemId = items.itemId where cart.cookieId = '" . GetCartId() . "'
order
by items.itemName asc"),$connection);

... we can see that you include header_aurelis.php, which presumably
outputs
the initial part of your HTML, before you do

  $show_cart = @mysql_query ... ;

which includes a call to GetCartId() -- which will attempt to set the
cartId
cookie if it's not already set, and will fail with the "headers already
sent" error.

So, overall, I'd say you've got to get/set your cartId earlier in the
game
-- and certainly before you call or include anything that outputs actual
page content.

This analysis also explains why the error is intermittent -- someone who
has
set the cartId cookie once will probably not see the error again until
after
the cookie expires 30 days later!

Hope this helps (and you followed my somewhat rambling explanation!)

Cheers!

Mike

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