在codeigniter中重定向时无法修改标头信息

Question

我对codeiginter真的很陌生。我正在尝试创建一个博客站点。在那里，我创建了一个评论博客帖子的功能。在评论之前，用户需要登录该站点。因此，如果未登录的用户尝试发表评论，我想将其重定向到登录页面。我使用重定向功能将用户重定向到登录页面。

然后我收到此错误

我的代码是： （控制器）

public function add_review($pots_id)
{
    $form_data = $this->input->post();
    $this->load->model("blog_model");
    if(isset($form_data['comment']))
    { 
        $state = $this->isBad($form_data['comment']);
    }
    else
    {
        $state = $this->isBad("");
    }

    $this->data['blog_comment_back'] = -1;
    if(isset($_SESSION['Username']))
    {
        if(strcmp($state, "-1")==0)
        {

            if(strcmp(substr($pots_id,0,3), "Art")==0)
            {
                $status = $this->blog_model->add_review($pots_id, $form_data,$_SESSION['Username']);
            }        
        }
        else
        {
            $msg = "Your comment has inappropriate word. Please correct them";
            $this->data['blog_comment_back'] = $state;
            echo "<script>alert('Please check your comments. You have got inappropriate words in it.');</script>";
        }
    }
    else{
        echo "<script>alert('Please login to comment.');</script>";
        $this->session->set_flashdata('redirectToCurrent',  $form_data);
        $this->session->set_flashdata('crurrentData', current_url());
        redirect(base_url().'welcome/login','refresh');
        // var_dump($this->session->flashdata('crurrentData'));
        // var_dump($this->session->flashdata('redirectToCurrent'));
    }


        $this->data['blog_s'] = $this->blog_model->blog_singel_load($pots_id); // Get the article details
        $this->data['blog_review'] = $this->blog_model->get_review($pots_id);
        $this->load->view('blog-single',$this->data);

}

这是我的blog_model.php

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');

class Blog_model extends CI_Model
{
    public function load_blog_details() {
         $this->db->select("*");
         $this->db->from('Articles');
         $query = $this->db->get();
         return $query->result();
    }

    public function blog_singel_load($post_id) {
         $this->db->select("*");
         $this->db->from('Articles');
         $this->db->where('Article_ID',$post_id);
         $query = $this->db->get();
         return $query->result();
    }

    public function get_review($post_id)
    {
         $this->db->select("*");
         $this->db->from('Articel_review');
         $this->db->where('Articel_ID',$post_id);
         $query = $this->db->get();
         return $query->result();
    }
    public function add_review($id,$form_data, $uname) {

            $data = array(
           'Articel_ID' => $id,
           'user_name' => $uname,
           'comment' => $form_data['comment'] 
        );
        //var_dump($this->db->insert('Articel_review', $data));
        return $this->db->insert('Articel_review', $data); 


    }

}