Impara Storing and Destroying Session Data | Understanding PHP Sessions

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When you need to store information about a user across multiple requests in PHP, the $_SESSION superglobal is your main tool. This special associative array is available after you call session_start(), and it allows you to save data that persists as long as the session is active. You can set, retrieve, and manipulate variables in $_SESSION just like a regular array, making it a convenient way to keep track of user preferences, login states, or other temporary data without exposing it to the client.

session_store.php


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<?php
session_start();

// Store data in the session
$_SESSION["username"] = "alice";
$_SESSION["role"] = "admin";

// Retrieve data from the session
echo "Username: " . $_SESSION["username"] . "<br>";
echo "Role: " . $_SESSION["role"];
?>

In the previous script, you saw how to set and retrieve session variables after starting a session. When you want to remove data from the session, PHP provides two main functions. To remove a specific variable, you can use unset($_SESSION['key']). If you want to clear all session variables but keep the session itself active, use session_unset(). To destroy the session entirely, including all its data and the session ID, call session_destroy(). These functions are essential for managing session data securely, especially when a user logs out or when sensitive data should no longer be accessible.

session_destroy.php


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<?php
session_start();

// Unset all session variables
session_unset();

// Destroy the session
session_destroy();

echo "Session data cleared and session destroyed.";
?>

To keep your application secure and prevent data leakage between users or sessions, always clean up session data when it is no longer needed. For example, after a user logs out, use both session_unset() and session_destroy() as shown above. This ensures that no sensitive information remains accessible in the session, and the session ID is invalidated. Referencing the earlier examples, remember to start your session before manipulating $_SESSION, and always clear session data when finishing a sensitive operation.

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