Formidable Forms - Limit Amount of Tickets that Can Be Purchased

formidable-forms-ticket-limit.php

<?php 

add_filter('frm_validate_field_entry', 'max_100_tickets', 10, 3);
function max_100_tickets( $errors, $posted_field, $posted_value ) {
    $field_id = 249; // change this to the ID of the Quantity Field
    $tickets_requested = $_POST['item_meta'][249]; //Change 249 to the field containing the number of tickets being requested
    $remaining_tickets = $_POST['item_meta'][281]; //Change 281 to the calculated field containing the number of remaining tickets
    if( $tickets_requested > $remaining_tickets ) {
      $errors[ 'field' . $field_id ] = "You've requested more tickets than available. Please try again";
    }
    return $errors;
}