jquery，sessions＆php session_id（）;

Question

I have a session_id which I am using to identify the user in a shopping basket type application.

The session_id is stored in the database as the session id.

When I update the cart, the session_id, product_id and qty are stored in the Basket table.

I am trying to add an item to the Basket, then show the updated basket on the screen without page refresh using jquery.

Do I store the session id in a hidden html field or is there a better way of getting jQuery to know what the session_id is?

UPDATE: Ok, so now based on answers and comments below, I don't really want to be using the session id in a hidden field. I certainly don't want to show the session id within the html page.

I may need to backtrack a little...

When ajax is calling my update basket function, I am faced with the following error...

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at ..... /ajaxData.php on line 105

The code I am using to start the session is...

if (!session_id()){
session_start();
}

I don't really understand what this warning means, so this is why I was thinking of sending the session id via the hidden html field.

I guess the solution is to fix what the warning was and try to do things properly...

Any suggestions on my warning message?

Answer 1

IMO all session data must be managed in the server, if you really need it in the front-end get it asynchronously. For example:

1.- jquery stuff

$.get(
        window.location.href,
        {
            get_session_id : 1
        },
    function(data) {
    var session_id = data.session_id
    if ("" == session_id){
            // alert user
            // give a friendly way to proceed without loss user's time
            // return;
    }
    // use session_id
}, "json");

UPDATE To avoid Warning: session_start() [function.session-start]... error put this snippet early as possible in your script. BEFORE any html output.

2.- server stuff

// none output before this snippet

if ($_GET['get_session_id'])
{
    // get $session_id
    $output['session_id'] = $session_id ? $session_id : '';
    echo json_encode($output);
    exit;
}

UPDATE 2:

The reason I propose to you this solution is that I think it is better to get the session ID dynamically when needed, instead of having it stored in a static way, is that this identifier may be modified, deleted, etc., while the user takes his time to fill a form.
Unfortunately this defect is very common and annoying. Submit a form and instead of being processed, we are redirected to a login page, losing all data sent.