Are there any best practices for maintaining form data in PHP when errors are found during validation?

When errors are found during form validation in PHP, it is important to maintain the form data so that the user does not have to re-enter the information. One common approach is to store the form data in session variables and repopulate the form fields with the saved values when displaying the form again. 

```php
// Start the session
session_start();

// Check if form is submitted
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // Validate form data
    // If validation fails, store form data in session
    $_SESSION['form_data'] = $_POST;
    // Redirect back to the form page
    header("Location: form.php");
    exit;
} else {
    // Check if there is saved form data in session
    $form_data = isset($_SESSION['form_data']) ? $_SESSION['form_data'] : [];
    // Clear the saved form data from session
    unset($_SESSION['form_data']);
}

// Display the form with repopulated values
```
In this code snippet, we store the form data in session variables if validation fails. When displaying the form again, we check if there is saved form data in session and repopulate the form fields with the saved values. This ensures that the user does not lose their input when errors occur during form validation.

Keywords

form data validation error handling PHP functions data persistence

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