How can the issue of form double-clicking be effectively addressed in PHP to prevent multiple form submissions?

Form double-clicking can be effectively addressed in PHP by using a token-based approach. When a form is submitted, a unique token is generated and stored in a session variable. Upon submission, the token is checked to ensure that the form is only processed once. This prevents multiple form submissions and helps maintain data integrity. 

```php
session_start();

if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    if (!isset($_SESSION['token'])) {
        $_SESSION['token'] = bin2hex(random_bytes(32));
    }

    if ($_POST['token'] == $_SESSION['token']) {
        // Process form data
        unset($_SESSION['token']);
    } else {
        // Handle duplicate form submission
    }
}
```
In this code snippet, a token is generated when the form is loaded and stored in a session variable. Upon form submission, the token is checked to ensure it matches the token stored in the session. If they match, the form data is processed, and the token is unset to prevent further submissions. If the tokens do not match, it indicates a duplicate form submission, and appropriate action can be taken.

Keywords

PHP form submission prevent double-clicking CSRF token session management

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