設定路由 application/config/routes.php

$route['api/v1/url/(:any)']['GET'] = 'api/v1/url/get/$1';

寫Controller application/controllers/api/v1/url.php

public function get($url_shorten) {
    $database = $this->load->database('default',true); //設定database連線
    $query = $database //檢查紀錄是否存在
        ->from('urls')
        ->where('url_shorten',$url_shorten)
        ->get();
    if (!$query -> num_rows() > 0) { //不大於零: 不存在 
        http_response_code(404); //回應HTTP 404 Not Found
        print_r(
            json_encode(
                array(
                    'status' => 'error',
                    'code' => 404,
                    'message' => 'not-found'
                )
            )
        );
        die();
    } else {
        echo json_encode(
            array(
                'status' => 'success',
                'code' => 200,
                'data' => $query->result_array()
            )
        );
    }
}