private function process_update_post(CalendarEvent $old_event)
 {
     $updating = (bool) $old_event->getId();
     if (isset($_POST['save']) && isset($_POST['event'])) {
         $post_data = array_map('trim', $_POST['event']);
         // validate the data and create error message
         $errors = $this->validate_post_data($post_data);
         if ($errors) {
             Flash::setNow('error', 'There are errors in the form.');
             return array('event' => $old_event, 'updating' => $updating, 'post_data' => $post_data, 'errors' => $errors);
         }
         // if we'are updating an event, some data should be added to $post_data
         if ($updating) {
             $post_data['id'] = $old_event->getId();
             $post_data['created_by_id'] = $old_event->getAuthorID();
         }
         $updated_event = new CalendarEvent($post_data);
         $saved = $updated_event->save();
         if ($saved) {
             Flash::set('success', $updating ? __('The event has been updated.') : __('A new event has been created.'));
             redirect(get_url('plugin/' . CALENDAR_ID . '/events'));
         } else {
             Flash::setNow('error', __('Could not update this event!'));
             return array('event' => $updated_event, 'updating' => $updating);
         }
     }
     // if it's not POST, just return $old_event
     return array('event' => $old_event, 'updating' => $updating);
 }
plugin/calendar/update_event" method="post">
    <fieldset style="padding:0.5em;">
        <legend style="padding: 0em 0.5em 0em 0.5em; font-weight: bold;"><?php 
echo __('Edit the event');
?>
</legend>
            <table class="fieldset" cellspacing="0" cellpadding="0" border="0">
                <?php 
if ($edit_event) {
    ?>
                    <input type="hidden" name="event[id]" value="<?php 
    echo $event->getId();
    ?>
" />
                    <input type="hidden" name="event[created_by_id]" value="<?php 
    echo $event->getAuthorID();
    ?>
" />
                <?php 
}
?>
                
                <tr>
                    <td class="label"><label for="event-title"><?php 
echo __('Title');
?>
</label></td>
                    <td class="field"><input type="text" id="notes-title" name="event[title]" class="textbox" value="<?php 
echo $event->getTitle();
?>
" /></td>