+ * Add the field to the checkout
+ * https://docs.woocommerce.com/document/tutorial-customising-checkout-fields-using-actions-and-filters/
+add_action( 'woocommerce_after_order_notes', 'my_custom_checkout_field' );
+function my_custom_checkout_field( $checkout ) {
+ echo '<div id="my_custom_checkout_field">';
+ woocommerce_form_field( 'student_names', array(
+ 'class' => array('my-field-class form-row-wide'),
+ 'label' => __('<strong>Student Names</strong>'),
+ 'placeholder' => __('Enter the names of all students and include their age if they are under 18.'),
+ ), $checkout->get_value( 'student_names' ));
+add_action('woocommerce_checkout_process', 'my_custom_checkout_field_process');
+function my_custom_checkout_field_process() {
+ // Check if set, if its not set add an error.
+ if ( ! $_POST['student_names'] )
+ wc_add_notice( __( 'Please enter the names and their age if they are under 18.' ), 'error' );
+ * Update the order meta with field value
+add_action( 'woocommerce_checkout_update_order_meta', 'my_custom_checkout_field_update_order_meta' );
+function my_custom_checkout_field_update_order_meta( $order_id ) {
+ if ( ! empty( $_POST['student_names'] ) ) {
+ update_post_meta( $order_id, 'Student Names', sanitize_text_field( $_POST['student_names'] ) );
+ * Display field value on the order edit page
+add_action( 'woocommerce_admin_order_data_after_billing_address', 'my_custom_checkout_field_display_admin_order_meta', 10, 1 );
+function my_custom_checkout_field_display_admin_order_meta($order){
+ echo '<p><strong>'.__('Student Names').':</strong> ' . get_post_meta( $order->id, 'Student Names', true ) . '</p>';
