RTMediaActivityModel::update PHP Method

    function update($data, $where)
    {
        $where['blog_id'] = get_current_blog_id();
        return parent::update($data, $where);
    }

 function rtm_change_activity_privacy()
 {
     $data = $_POST;
     if (wp_verify_nonce($data['nonce'], 'rtmedia_activity_privacy_nonce')) {
         $rtm_activity_model = new RTMediaActivityModel();
         $is_ac_privacy_exist = $rtm_activity_model->check($data['activity_id']);
         $privacy = intval($data['privacy']);
         $activity_id = intval($data['activity_id']);
         if (!$is_ac_privacy_exist) {
             // Very first privacy entry for this activity
             $status = $rtm_activity_model->insert(array('privacy' => $privacy, 'activity_id' => $activity_id, 'user_id' => get_current_user_id()));
         } else {
             // Just update the existing value
             $status = $rtm_activity_model->update(array('privacy' => $privacy), array('activity_id' => $activity_id));
         }
         // update privacy of corresponding media
         $media_model = new RTMediaModel();
         $activity_media = $media_model->get(array('activity_id' => $activity_id));
         if (!empty($activity_media) && is_array($activity_media)) {
             foreach ($activity_media as $single_media) {
                 $where = array('id' => $single_media->id);
                 $columns = array('privacy' => $privacy);
                 // update media privacy
                 $media_model->update($columns, $where);
             }
         }
         if ($status === false) {
             $status = 'false';
         } else {
             $status = 'true';
         }
         echo $status;
         wp_die();
     }
 }