What are the best practices for handling form data retention in PHP to avoid loss of user input?

When handling form data retention in PHP to avoid loss of user input, it is important to use sessions or cookies to store the form data temporarily. This allows the user to navigate away from the page and return without losing their input. Additionally, using client-side validation can help prevent the need for the user to re-enter data if there are errors in the form submission. 

// Start a session to store form data
session_start();

// Check if form data has been submitted
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // Store form data in session variables
    $_SESSION['form_data'] = $_POST;
    
    // Redirect to the same page to avoid resubmission on page refresh
    header("Location: ".$_SERVER['PHP_SELF']);
    exit;
}

// Retrieve form data from session if available
if(isset($_SESSION['form_data'])){
    $form_data = $_SESSION['form_data'];
    unset($_SESSION['form_data']); // Clear form data from session
} else {
    $form_data = array(); // Initialize form data array
}

// Use $form_data array to pre-fill form fields

Keywords

POST method $_POST superglobal session variables form validation data sanitization

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