我的codeigniter登录代码工作了一段时间并停止

Question

My codeigniter login code works for a time and then stops. And I noticed also that anytime I clear my browser cache and other parameters, it also stops working until I change the username and password again.

This is my controller code

// Log in user
    public function login(){
        $data['title'] = 'Sign In';

        $this->form_validation->set_rules('username', 'Username', 'required');
        $this->form_validation->set_rules('password', 'Password', 'required');

        if($this->form_validation->run() === FALSE){
            $this->load->view('templates/header');
            $this->load->view('admins/index', $data);
            $this->load->view('templates/footer');
        } else {

            // Get username
            $username = $this->input->post('username');
            // Get and encrypt the password
            $password = md5($this->input->post('password'));

            // Login user
            $user_id = $this->admin_model->login($username, $password);

            if($user_id){
                // Create session
                $user_data = array(
                    'user_id' => $user_id,
                    'username' => $username,
                    'logged_in' => true
                );

                $this->session->set_userdata($user_data);

                // Set message
                //set message
                $this->session->set_flashdata('admin_loggedin', 'Welcome, You are now logged in');

                redirect('admins/view');
            } else {
            // Set message
                $this->session->set_flashdata('login_failed', 'Oops, Your username or password is not correct!');

                redirect('admins');
            }       
        }

And this is my model code

// Log user in
    public function login($username, $password){
        // Validate
        $this->db->where('username', $username);
        $this->db->where('password', $password);

        $result = $this->db->get('admins');

        if($result->num_rows() == 1){
            return $result->row(0)->id;
        } else {
            return false;
        }
    }

This is my .htaccess code

 RewriteEngine On
RewriteCond $1 !^(index\.php|assets|images|js|css|uploads|favicon.png)
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ ./index.php/$1 [L]
RewriteCond %{REQUEST_URI} ^system.*

Answer 1

If think that, by default, CodeIgniter uses sessions to store logged in user. So, this might be your scenario - by clearing the browser cache, you clear the cookie that stores the session ID and the session gets invalidated, hence causing you to be logged out.