規劃路由 /application/config/routes.php

$route['(:any)'] = 'url/redirect/$1'; //要放在最下面!

寫Controller /application/controllers/url.php

<?php
defined('BASEPATH')or show_403();

class Url extends CI_Controller
{
    function redirect($surl) {
        $database = $this->load->database('default',true); //連接至default設定檔
        $query = $database //SELECT * FROM `urls` WHERE `url_shorten` = "$dest";
            ->from('urls')
            ->where('url_shorten',$surl)
            ->get();
        if ($query -> num_rows() > 0) { //撿查url是否存在
            $query = $query->result_array(); //取得查詢結果
            redirct($query[0]['url_dest']) //執行301 Redirect
        } else {
            show_404(); //不存在回復404 Not Found
        }
    }
}

現在應該可以正常運作了！利用昨天的api生成一個短網址來測試看看吧！
有問題歡迎把錯誤訊息丟上來！