Donation notes field example for PMPro Donations (Updated).

my_pmprodon_donation_notes.php

<?php

/**
 * Donation notes.
 * Edit the copy below.
 * Add to a custom plugin.
 * Notes are now saved into the order meta instead of the order notes.
 */

// Show the donation notes field at checkout (Always visible)
function my_pmprodon_donation_notes() {
    global $pmpro_level;

    // Check if this level has donations
    $donfields = get_option('pmprodon_' . $pmpro_level->id);

    // No donations? Just return
    if (empty($donfields) || empty($donfields['donations'])) {
        return;
    }

    // Grab data
    $pmpro_donation_notes = isset($_REQUEST['pmpro_donation_notes']) ? sanitize_text_field($_REQUEST['pmpro_donation_notes']) : '';

    // Show field and instructions (always visible)
    ?>
    <p class="pmpro_small">All donations are designated for the general fund.</p>
    <p class="donation_notes_instructions">
        Your donation can be earmarked for the general fund, the scholarship fund, or a combination of both. You can also request a specific use for your donation. Let us know in the field below.
    </p>
    <textarea id="pmpro_donation_notes" name="pmpro_donation_notes" style="width: 100%; height: 100px;"><?php echo esc_textarea($pmpro_donation_notes); ?></textarea>
    <?php
}
add_action('pmpro_checkout_after_level_cost', 'my_pmprodon_donation_notes', 15);

// Save donation notes into order meta
function my_pmprodon_save_donation_notes_to_order($order) {
    if (!empty($_REQUEST['pmpro_donation_notes'])) {
        $donation_notes = sanitize_text_field($_REQUEST['pmpro_donation_notes']);
        update_post_meta($order->id, 'pmpro_donation_notes', $donation_notes);
    }
}
add_action('pmpro_added_order', 'my_pmprodon_save_donation_notes_to_order');

// Retrieve donation notes when viewing order details
function my_pmprodon_show_donation_notes($order) {
    $donation_notes = get_post_meta($order->id, 'pmpro_donation_notes', true);
    
    if (!empty($donation_notes)) {
        echo '<p><strong>Donation Notes:</strong> ' . esc_html($donation_notes) . '</p>';
    }
}
add_action('pmpro_after_order_settings', 'my_pmprodon_show_donation_notes');

// Save donation notes in session to persist on checkout reloads
function my_pmprodon_save_donation_notes_to_session() {
    if (!empty($_REQUEST['pmpro_donation_notes'])) {
        $_SESSION['pmpro_donation_notes'] = sanitize_text_field($_REQUEST['pmpro_donation_notes']);
    }
}
add_action('pmpro_checkout_before_processing', 'my_pmprodon_save_donation_notes_to_session');

// Retrieve saved donation notes from session when returning to checkout
function my_pmprodon_retrieve_donation_notes_from_session() {
    if (!empty($_SESSION['pmpro_donation_notes'])) {
        $_REQUEST['pmpro_donation_notes'] = $_SESSION['pmpro_donation_notes'];
    }
}
add_action('pmpro_checkout_after_form', 'my_pmprodon_retrieve_donation_notes_from_session');