Codeigniter错误选择查询无法检查用户输入

Question

我是Codeigniter的新手，正在使用3.1.5版本。 以下是我的用户登录功能。

class Auth extends CI_Controller
{
    public function login()
    {
        // Load Login View
        $this->load->view('login');
        // validate form
        $this->form_validation->set_rules('username','Username','required');
        $this->form_validation->set_rules('password','Password','required|min_length[5]');
        if($this->form_validation->run()== true){
            $username = $_POST['username'];
            $password = $_POST['password'];
            // check user in database
            $this->db->select("*");
            $this->db->from("users");
            $this->db->where(array("username"=>$username,"password"=>$password));
            $query = $this->db->get();
            $user_data  = $query->row();
            // check if user exists or not
            if($user_data->username){
                // show temporary success message
                $this->session->set_flashdata("success","User successfully logged in");
                // set temporary sesstion variables
                $_SESSION['user_logged'] = TRUE;
                $_SESSION['username'] = $user_data->username;
            }else{
                $this->session->set_flashdata("error","Invalid username, user not exist");
            }
        }
    }

当我提供用户名（如用户名和密码）时，出现以下错误，无法解决。

Severity: Notice

Message: Trying to get property of non-object

Filename: controllers/Auth.php

Line Number: 29

Backtrace:

File: D:\xampp\htdocs\ci315\application\controllers\Auth.php
Line: 29
Function: _error_handler

File: D:\xampp\htdocs\ci315\index.php
Line: 315
Function: require_once

行号29正是从这里开始

      if($user_data->username){
       // show temporary success message
       $this->session->set_flashdata("success","User successfully logged in");
         // set temporary sesstion variables
         $_SESSION['user_logged'] = TRUE;
         $_SESSION['username'] = $user_data->username;
         }else{
         $this->session->set_flashdata("error","Invalid username, user not exist");
         }

如果我评论以上部分，则没有错误。 请建议我在哪里做错了。 任何帮助将不胜感激，在此先感谢。

Answer 1

在下面的代码中使用可以正常工作。 使用if（$ query-> num_rows（）> 0）代替if（$ user_data-> username）和$ query-> row（）-> username代替$ user_data-> username

class Auth extends CI_Controller
{
    public function login()
    {
        // Load Login View
        $this->load->view('login');
        // validate form
        $this->form_validation->set_rules('username','Username','required');
        $this->form_validation->set_rules('password','Password','required|min_length[5]');
         if($this->form_validation->run()== true){
            $username = $_POST['username'];
            $password = $_POST['password'];
            // check user in database
            $this->db->select("*");
            $this->db->from("users");
            $this->db->where(array("username"=>$username,"password"=>$password));
            $query = $this->db->get();

            if($query->num_rows() > 0){
                // show temporary success message
                $this->session->set_flashdata("success","User successfully logged in");
                // set temporary sesstion variables
                $_SESSION['user_logged'] = TRUE;
                $_SESSION['username'] = $query->row()->username;
            }else{
                $this->session->set_flashdata("error","Invalid username, user not exist");
            }
        }
    }
}