php - 从 CodeIgniter 中的核心 Controller 获取数据

Question

我正在开发一款社交网络应用。我遇到一个问题，我试图从数据库中名为 users 的表中获取名称和用户名。为了能够在不单独访问所有 Controller 的情况下执行此操作，我必须创建一个名为 MY_Controller 的核心 Controller 。

问题如下(MY_Controller 没有公共(public) $users):

<?php

class MY_Controller extends CI_Controller
{

//public $users = array('username' => $this->input->post('username')); 


    function __construct()
    {
        parent::__construct();

        //Get user data to make it available for both Admin and Public Controllers
        $this->load->model('User_model');
        $this->users = $this->User_model->get_list();

        //Load Menu Library
        $this->load->library('menu');
        $this->pages = $this->menu->get_pages();

        // Brand/Logo
        $this->favicon = 'https://blogpersonal.net/wp-content/uploads/2017/08/favicon-v2-150x150.png';
        $this->brand = 'Some Name';
        $this->description = 'Some Description';
        $this->credits = 'https://blogpersonal.net/';
        $this->version = '1.1.1';
    }
}

class Admin_Controller extends MY_Controller
{

    function __construct()
    {
        parent::__construct();

        if (!$this->session->is_admin) {
            redirect('admin/login');
        }

        //some code here

    }
}

class Public_Controller extends MY_Controller{
    function __construct(){
        parent::__construct();

        //some code here

    }

}

class Social_Controller extends MY_Controller
{

    function __construct()
    {
        parent::__construct();

        if (!$this->session->is_member) {
            redirect('dashboard/login');
        }

        //some code here

    }
}

如您所见，我使用 __construct 函数加载了 User_model，使其可用并在所有 Controller 中使用它。

我想在名为 templates 的文件夹中获取数据。 View >模板>任何文档但是当我尝试在这样的 View 中获取它时:

    <?php if($this->users) : ?>
        <li class="dropdown user user-menu">
          <!-- Menu Toggle Button -->
          <a href="#" class="dropdown-toggle" data-toggle="dropdown">
            <!-- The user image in the navbar-->
            <img src="<?php echo base_url(); ?>assets/img/user2-160x160.jpg" class="user-image" alt="User Image">
            <!-- hidden-xs hides the username on small devices so only the image appears. -->
            <span class="hidden-xs"><?php echo $this->users['username']; ?></span>
          </a>

        </li>
    <?php endif; ?>

这是旧错误。它向我显示一个错误。难道我做错了什么？有人可以解释一下如何解决它吗？这是我第一次无法获取数据。这是我得到的结果:

A PHP Error was encountered

Severity: Notice

Message: Undefined variable: users

Filename: Templates/public.php

Line Number: 161

Backtrace:

File: C:\xampp\htdocs\codeigniter\application\views\Templates\public.php Line: 161 Function: _error_handler

File: C:\xampp\htdocs\codeigniter\application\libraries\Template.php Line: 34 Function: view

File: C:\xampp\htdocs\codeigniter\application\controllers\Pages.php Line: 12 Function: load

File: C:\xampp\htdocs\codeigniter\index.php Line: 315 Function: require_once

这是我的模型(User_model)，以防您可能需要它:

<?php

class User_model extends CI_MODEL
{

    function __construct()
    {
        parent::__construct();
        $this->table = 'users';
    }

    public function get_list()
    {
        $query = $this->db->get($this->table);
        return $query->result();
    }

    public function get($id)
    {
        $this->db->where('id', $id);
        $query = $this->db->get($this->table);
        return $query->row();
    }

    public function add($data)
    {
        $this->db->insert($this->table, $data);
    }

    public function update($id, $data)
    {
        $this->db->where('id', $id);
        $this->db->update($this->table, $data);
    }

    public function delete($id)
    {
        $this->db->where('id', $id);
        $this->db->delete($this->table);
    }

    public function login($username, $password)
    {
        $this->db->select('*');
        $this->db->from($this->table);
        $this->db->where('username', $username);
        $this->db->where('password', $password);
        $this->db->limit(1);

        $query = $this->db->get();

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

现在，根据向我建议的更改，它现在显示一个新错误:

新错误:

A PHP Error was encountered

Severity: Notice Message: Undefined index: username Filename: Templates/public.php Line Number: 168

Backtrace:

File: C:\xampp\htdocs\codeigniter\application\views\Templates\public.php Line: 168 Function: _error_handler

File: C:\xampp\htdocs\codeigniter\application\libraries\Template.php Line: 34 Function: view

File: C:\xampp\htdocs\codeigniter\application\controllers\public\Dashboard.php Line: 13 Function: load

File: C:\xampp\htdocs\codeigniter\index.php Line: 315 Function: require_once

现在，如果取消注释核心 Controller (MY_Controller)中的公共(public) $users ，它也会显示一个新错误:

公共(public) $users 在 __construct 函数之外出现新错误

Fatal error: Constant expression contains invalid operations in C:\xampp\htdocs\codeigniter\application\core\MY_Controller.php on line 6 A PHP Error was encountered

Severity: Compile Error

Message: Constant expression contains invalid operations

Filename: core/MY_Controller.php

Line Number: 6

Backtrace:

这是我尝试将数据获取到的图片:

我做错了什么吗？感谢您的帮助。

这是 View (public.php)文件:

<ul class="nav navbar-nav">
          <?php if(!$this->session->is_member) : ?>
          <li><?php echo anchor('public/users/login', 'Login'); ?></li>
          <li><?php echo anchor('public/users/register', 'Register'); ?></li>
          <?php else : ?>
            <!-- Messages: style can be found in dropdown.less-->
            <li class="dropdown messages-menu">
              <!-- Menu toggle button -->
              <a href="#" class="dropdown-toggle" data-toggle="dropdown">
                <i class="fa fa-envelope-o"></i>
                <span class="label label-success">4</span>
              </a>
              <ul class="dropdown-menu">
                <li class="header">You have 4 messages</li>
                <li>
                  <!-- inner menu: contains the messages -->
                  <ul class="menu">
                    <li><!-- start message -->
                      <a href="#">
                        <div class="pull-left">
                          <!-- User Image -->
                          <img src="<?php echo base_url(); ?>assets/img/user2-160x160.jpg" class="img-circle" alt="User Image">
                        </div>
                        <!-- Message title and timestamp -->
                        <h4>
                          Support Team
                          <small><i class="fa fa-clock-o"></i> 5 mins</small>
                        </h4>
                        <!-- The message -->
                        <p>Why not buy a new awesome theme?</p>
                      </a>
                    </li>
                    <!-- end message -->
                  </ul>
                  <!-- /.menu -->
                </li>
                <li class="footer"><a href="#">See All Messages</a></li>
              </ul>
            </li>
            <!-- /.messages-menu -->
            <!-- Notifications Menu -->
            <li class="dropdown notifications-menu">
              <!-- Menu toggle button -->
              <a href="#" class="dropdown-toggle" data-toggle="dropdown">
                <i class="fa fa-bell-o"></i>
                <span class="label label-warning">10</span>
              </a>
              <ul class="dropdown-menu">
                <li class="header">You have 10 notifications</li>
                <li>
                  <!-- Inner Menu: contains the notifications -->
                  <ul class="menu">
                    <li><!-- start notification -->
                      <a href="#">
                        <i class="fa fa-users text-aqua"></i> 5 new members joined today
                      </a>
                    </li>
                    <!-- end notification -->
                  </ul>
                </li>
                <li class="footer"><a href="#">View all</a></li>
              </ul>
            </li>
            <!-- Tasks Menu -->
            <li class="dropdown tasks-menu">
              <!-- Menu Toggle Button -->
              <a href="#" class="dropdown-toggle" data-toggle="dropdown">
                <i class="fa fa-flag-o"></i>
                <span class="label label-danger">9</span>
              </a>
              <ul class="dropdown-menu">
                <li class="header">You have 9 tasks</li>
                <li>
                  <!-- Inner menu: contains the tasks -->
                  <ul class="menu">
                    <li><!-- Task item -->
                      <a href="#">
                        <!-- Task title and progress text -->
                        <h3>
                          Design some buttons
                          <small class="pull-right">20%</small>
                        </h3>
                        <!-- The progress bar -->
                        <div class="progress xs">
                          <!-- Change the css width attribute to simulate progress -->
                          <div class="progress-bar progress-bar-aqua" style="width: 20%" role="progressbar" aria-valuenow="20" aria-valuemin="0" aria-valuemax="100">
                            <span class="sr-only">20% Complete</span>
                          </div>
                        </div>
                      </a>
                    </li>
                    <!-- end task item -->
                  </ul>
                </li>
                <li class="footer">
                  <a href="#">View all tasks</a>
                </li>
              </ul>
            </li>
            <!-- User Account Menu -->
            <?php if($this->users) : ?>
                <li class="dropdown user user-menu">
                  <!-- Menu Toggle Button -->
                  <a href="#" class="dropdown-toggle" data-toggle="dropdown">
                    <!-- The user image in the navbar-->
                    <img src="<?php echo base_url(); ?>assets/img/user2-160x160.jpg" class="user-image" alt="User Image">
                    <!-- hidden-xs hides the username on small devices so only the image appears. -->
                    <span class="hidden-xs"><?php echo $this->users['username']; ?></span>
                  </a>
                  <ul class="dropdown-menu">
                    <!-- The user image in the menu -->
                    <li class="user-header">
                    <img src="<?php echo base_url(); ?>assets/img/user2-160x160.jpg" class="img-circle" alt="User Image">
                      <p><?php echo $this->users['name']; ?> - Web Developer<small>Member since Nov. 2012</small></p>
                    </li>
                    <!-- Menu Body -->
                    <li class="user-body">
                      <div class="row">
                        <div class="col-xs-4 text-center">
                          <a href="#">Followers</a>
                        </div>
                        <div class="col-xs-4 text-center">
                          <a href="#">Sales</a>
                        </div>
                        <div class="col-xs-4 text-center">
                          <a href="#">Friends</a>
                        </div>
                      </div>
                      <!-- /.row -->
                    </li>
                    <!-- Menu Footer-->
                    <li class="user-footer">
                      <div class="pull-left">
                        <a href="#" class="btn btn-default btn-flat">Profile</a>
                      </div>
                      <div class="pull-right">
                        <a href="<?php echo base_url(); ?>public/users/logout" class="btn btn-default btn-flat">Sign out</a>
                      </div>
                    </li>
                  </ul>
                </li>
            <?php endif; ?>
            <li>
                <a href="#" data-toggle="control-sidebar"><i class="fa fa-gears"></i></a>
            </li>
          <?php endif; ?>
          </ul>

Answer 1

您目前拥有此...而我仅在此处显示片段...

class MY_Controller extends CI_Controller
{
    function __construct()
    {
        parent::__construct();

        //Get user data to make it available for both Admin and Public Controllers
        $this->load->model('User_model');
        $data['users'] = $this->User_model->get_list();

<<<<snip>>>>

建议您将本地定义的 $data['users'] 转换为“属性”

所以我们现在有两个改变......

1 声明属性

2 设置属性。

class MY_Controller extends CI_Controller
{
    public $users = array(); // Add the property $user, safe def of an empty array

    function __construct()
    {
        parent::__construct();

        //Get user data to make it available for both Admin and Public Controllers
        $this->load->model('User_model');
        //$data['users'] = $this->User_model->get_list();
        // Give the property something to share. 
        $this->users = $this->User_model->get_list();


    <<<<snip>>>>

现在，所有扩展 MY_Controller 的 Controller 现在都可以访问在 MY_Controller 中创建的 $this->users...

因此，您可以在要使用它的地方引用 $this->users。

我建议您首先阅读类、属性、方法和继承。通常这足以让你变得危险。这需要一点时间来适应，但值得付出努力......

更新:在调用 View 的 Controller 中，您会执行以下操作$data['users'] = $this->users;

在您看来，您现在像以前一样将其称为 $users->field_name 。我们所做的就是在您的基类中定义 $users，现在可以通过 $this->users 访问它，以便扩展 MY_Controller 类的所有 Controller /方法都可以访问它。