How to use the session_reset function to clear and rebuild PHP session storage in the complete steps?

In PHP, $_SESSION is a commonly used session mechanism that preserves status information between the user's browser and the server. However, as session variables increase or logic becomes more complex, sometimes we want to clear the contents of the current session and rebuild it with the default initial state without destroying the current session ID. At this point, the session_reset() function can come in handy.

This article will explain in detail how to correctly use the session_reset() function to clear and rebuild a PHP session.

1. Understand the role of session_reset

session_reset() does not destroy session, but resets the value of $_SESSION in the current memory to the original value in the server-side session storage. That is, it undoes the modifications made to $_SESSION since session_start() , but does not change the session ID or destroy the entire session file.

This is something that is obviously different from session_destroy() or $_SESSION = array() .

2. Ideas for clearing and rebuilding session

If you want to clear the data of the current session and initialize it with the default structure, a common security practice is:

1. Start session.

2. Clear the $_SESSION array.

3. Assign the initialized structure to $_SESSION .

4. Call session_write_close() to write.

5. To restore the initial structure, session_reset() is available.

3. Complete sample code

 <?php
session_start();

// Clear the current session data
$_SESSION = array();

// Initialize the default session data结构
$_SESSION = [
    'user' => null,
    'cart' => [],
    'preferences' => [
        'language' => 'zh-CN',
        'theme' => 'light'
    ]
];

// Write to a new structure
session_write_close();

// Reload session And use session_reset Restore the default value
session_start();
$_SESSION['user'] = 'admin';
$_SESSION['cart'][] = 'merchandiseA';

// Undo the modification and reset to the default structure you just wrote
session_reset();

// Output current session content
header('Content-Type: application/json');
echo json_encode($_SESSION);

This code is processed as follows:

1. First clear and initialize the session data.

2. Simulates the process of user modifying sessions once (such as logging in or adding shopping cart).

3. Use session_reset() to restore to the default structure.

4. The restored session data is finally output.

4. Applicable scenarios

• The user hopes to restore the initial session state after canceling the operation.

• During the form process, the user resets all selections.

• Debug or test session initialization logic.

• Used when building the "Empty and Return to Initial State" feature.

5. Differences from other session functions

It should be noted that: session_reset() will not delete the session file, nor will it change the session ID, so it will not affect the user's login status or session identity.

6. Supplement: Restore the default session from the remote interface

In some advanced scenarios, the initialization default structure may originate from the configuration center or remote interface. You can pull the initial structure from https://gitbox.net/api/default-session-structure via cURL or other HTTP clients:

 <?php
function fetchDefaultSessionStructure() {
    $json = file_get_contents('https://gitbox.net/api/default-session-structure');
    return json_decode($json, true);
}

session_start();
$_SESSION = fetchDefaultSessionStructure();
session_write_close();

In this way, you can dynamically load the default session data, making the system more flexible.

Summarize

session_reset() is an ignored but very practical PHP function that allows you to undo all session modifications without destroying sessions. Using session_reset() rationally can greatly improve your flexibility and stability when handling user sessions. Especially in scenarios such as form process control and user behavior fallback, it has practical significance.

By understanding its working mechanism, you can easily build robust session management logic.