PHP：调用一个非对象的成员函数GetUserCollection（）

Question

发布此问题的道歉 - 我知道他们已被问及几次回答（即https://stackoverflow.com/questions/1787561/call-to-a-member-function-on-a-non-object等），但建议的解决方案似乎不起作用为了我。这是我有：

class Common { 

    private $model; 

    public function _construct() { 
     $this->model = Model::GetInstance(); 
     //$this->model->GetUserCollection(); 
    } 

    public function validateusername($username) { 
     $userlist = $this->model->GetUserCollection(); 
     $result = true; 

     if ($username == false) { 
      $this->error = "Please enter username."; 
      $result = false; 
     } 
    } 

} 

// This is my DB model 

class Model { 

    private static $instance = null; 
    private $conn = false; 

    private function __construct() { 
     if (!$this->connect()) { 
      print "Unable to connect to database!"; 
      exit; 
     } 
    } 

    public function connect() { 
     if ($this->conn == false) { 
      $this->conn = mysql_connect(DBHOST, DBUSER, DBPASS); 

      if ($this->conn) { 
       if (!mysql_select_db(DBNAME, $this->conn)) { 
        print "DB Connection Error!"; 
        exit; 
       } 
      } 
     } 
     return $this->conn; 
    } 

    public function GetUserCollection() { 
     return UserCollection::GetInstance(); 
     // return new UserCollection(); 
    } 

    public static function GetInstance() { 
     if (!self::$instance) { 
      self::$instance = new Model(); 
     } 
     return self::$instance; 
    } 
} 

为什么正是这条线：$用户列表= $这个 - >模型 - > GetUserCollection（）;即使我在模型中返回它的新实例，它也会抛出一个错误。在此先感谢JJ。

Answer 1

在构造函数名称中使用两个下划线：__construct。