注销时，PHP索引页面会发出会话未知错误

Question

I have a login and logout session for my index page.

So, it uses the email of user as session, and when user logs in, it gets the details from fb using his email which is stored in session.

But when the user logs out, it shows an error of

Notice: Undefined index: email in D:\xampp\htdocs\site\index.php

My code goes as:

<?php 
    //15 2 2015
    session_start();
?>
<?php 
    $email = $_SESSION['email'];
    $sql = "SELECT * FROM landlords WHERE email = '$email' ";
    $result = $conn->query($sql);
    if ($result->num_rows > 0) {                                
    while($row = $result->fetch_assoc()) {                                   
?>
<?php 
        echo '<li class="dropdown submenu">';
        echo '<a href="#" class="dropdown-toggle">'; echo ($row["name"]); echo '</a>';
        echo '<ul class="dropdown-menu">';
        echo '<li><a href="myaccount.php">My Account</a></li>';
        echo '<li><a href="logout.php">Log Out</a></li>';
      echo '</ul>';
        echo '</li>';
?>
<?php    }
             } else {
        echo '<li>  <a href="signin.php"><span class="icon-user"></span>Sign In</a></li>';
        }
?>

Ignore the multiple php openings.

So, when a user logs in, it works fine, but when a user logs out, it gives a error of

Notice: Undefined index: email in D:\xampp\htdocs\site\index.php

Any help is appreciated.

Answer 1

The issue is that you don't guard the situation where the email session var is unset, as is after session unset (logout). Try this:

$email = @$_SESSION['email'];
if (!empty($email)) {
    $sql = "SELECT * FROM landlords WHERE email = '$email' ";
    $result = $conn->query($sql);
}
if (isset($result) && $result->num_rows > 0) {

...