$json_string = '{ "is_error" : true, "errors" : "' . $e->message . '"}';
    }
    print $json_string;
    /**
    * Creating a new link under the list
    */
} else {
    if (!empty($_POST) && $_POST['form_action'] == 'create_link') {
        //TODO: check for empty fields
        $Links = new Links();
        $Links->user_id = $_SESSION['user']['id'];
        $Links->category_id = $_POST['category_id'];
        $Links->title = $_POST['title'];
        $Links->url = Validation::validate_url($_POST['url']);
        try {
            $Links->save_link();
            $json_string = '{ "errors" : "Link has been added successfully", "updated_category_id" : ' . $_POST['category_id'] . '}';
        } catch (PAException $e) {
            $json_string = '{ "is_error" : true, "errors" : "' . $e->message . '"}';
        }
        print $json_string;
    } else {
        if (!empty($_POST) && $_POST['form_action'] == 'remove_list') {
            $Links = new Links();
            $Links->user_id = $_SESSION['user']['id'];
            $Links->category_id = $_POST['category_id'];
            try {
                $Links->delete_category(true);
                $json_string = '{ "errors" : "List has been deleted successfully"}';
            } catch (PAException $e) {
                $json_string = '{ "is_error" : true, "errors" : "' . $e->message . '"}';
 public static function add_default_links($user_id)
 {
     require_once "api/CNNetworkLinks/CNNetworkLinks.php";
     require_once "api/CNLinks/CNLinks.php";
     $network_links = new NetworkLinks();
     $network_owner_id = PA::$network_info->type == MOTHER_NETWORK_TYPE ? SUPER_USER_ID : Network::get_network_owner(PA::$network_info->network_id);
     $condition = array('user_id' => $network_owner_id, 'is_active' => 1);
     $link_categories = $network_links->load_category($condition);
     // load category as set by network operator
     $Links = new Links();
     $error_array = array();
     //providing default links to the user, as set by network operator
     for ($counter = 0; $counter < count($link_categories); $counter++) {
         $param_array = array('category_name' => $link_categories[$counter]->category_name, 'user_id' => $user_id, 'created' => time(), 'changed' => time(), 'is_active' => ACTIVE);
         $Links->set_params($param_array);
         $category_id = $Links->save_category();
         // save network operator category as user's link category
         $network_lists = new NetworkLinks();
         $network_lists->user_id = $network_info->owner_id;
         $condition = array('category_id' => $link_categories[$counter]->category_id, 'is_active' => ACTIVE);
         $list_array = $network_lists->load_link($condition);
         // load list for network operator's category
         for ($i = 0; $i < count($list_array); $i++) {
             $param_array = array('title' => $list_array[$i]->title, 'url' => $list_array[$i]->url, 'category_id' => $category_id, 'created' => time(), 'changed' => time(), 'is_active' => ACTIVE);
             $Links->set_params($param_array);
             $Links->save_link();
             // save network operator list as user's list
         }
     }
 }