页面之间的会话变量丢失

Question

I have 3 .php files:

index.php

<?php
session_start();

if (isset($_SESSION['comp_id']))
{
    require_once 'scan_albums.php';
}
else
{
    require_once 'login.php';
}

echo "SESSION['comp_id']=" .$_SESSION['comp_id'];
?>

scan_ablums.php

<?php
session_start();
if (!isset($_SESSION["comp_id"]))
{
    header('Location: index.php');
}
//...
?>

login.php

<?php
session_start();
if (isset($_SESSION['comp_id']))
{
    header('Location: index.php');
}
$_SESSION['comp_id'] = 3;
?>

I invoke login.php via ajax:

$.ajax(
{
  type: 'POST',
  url: 'login.php',
  data: {'login': login, 'password': hpass},
  success: function(data)
  {
    console.log("ajax: [comp_id]=" + data + "\n");
    window.location = "index.php";
  }
});

After redirect to my index.php $_SESSION['comp_id'] is empty. What am I doing wrong here? Thanks in advance.

EDIT: Forgot to mention that these pages are in iframe app in social network. Maybe this is the problem?

EDIT: Problem is definitely in iframe. Sessions are fine ob my local machine. Any ideas how to fix it?

Answer 1

You must call session_start(); at the beginning of every page that uses the session.

Answer 2

http://pt2.php.net/manual/en/function.session-write-close.php

Try calling session_write_close(); after you do the "login"

Check the session_id in the pages to see if it's all equal.

Also see:

When session.use_trans_sid is enabled, the session_start() function will register an internal output handler for URL rewriting.

In session_start

Answer 3

Check with your hosting provider about the details of their PHP configuration, specifically how it handles session data.

Ideally compare their php.ini configuration with your local (working) configuration. Check the session section.