带有 Highcharts 的 codeigniter-数据不来控制器查看

Question

我尝试将 highcharts 库添加到我的 CI 项目中。所以我在我的控制器中尝试了 db query<?phpdefined('BASEPATH') OR exit('No direct script access allowed');class ChartController extends CI_Controller {  public function __construct() {       parent::__construct();       $this->load->database();    }     public function index()    {        $query = $this->db->query("SELECT SUM(numberofclick) as count FROM demo_click             GROUP BY YEAR(created_at) ORDER BY created_at");         $data['click'] = json_encode(array_column($query->result(), 'count'),JSON_NUMERIC_CHECK);        $query = $this->db->query("SELECT SUM(numberofview) as count FROM demo_viewer             GROUP BY YEAR(created_at) ORDER BY created_at");         $data['viewer'] = json_encode(array_column($query->result(), 'count'),JSON_NUMERIC_CHECK);        $this->load->view('my_chart', $data);    }}然后我尝试通过视图访问。我放置了以下代码来检查控制器的输出。<?php echo var_dump($this->_ci_cached_vars);?>然后我得到，以下输出没有值。这是什么问题？array (size=2)  'click' => string '[]' (length=2)  'viewer' => string '[]' (length=2)