不能访问子类PDO连接

Question

我有一个问题作出PDO连接访问在扩展类，例如：

class Model { 

public $connection; 

public function __construct(PDO $connection = null) 
{ 
    global $config; 
    $this->connection = $connection; 
    if ($this->connection === null) { 
     $this->connection = new PDO(
     'mysql:host='.$config['db_host'].';dbname='.$config['db_name'], $config['db_username'], $config['db_password']); 
     $this->connection->setAttribute(
      PDO::ATTR_ERRMODE, 
      PDO::ERRMODE_EXCEPTION 
     ); 
    } 
} 

而另一扩展类模型

class User extends Model { 
    public function someFunction(){ 
     // how can I access the pdo connection in the parent constructer here? 
    } 
} 

这就是症结我不想访问在子类中的构造函数中创建的父连接的问题，非常感谢。

Answer 1

由于构造函数不是在PHP隐式调用，您需要添加至少某些行，事后只使用$this：

class User extends Model { 

    public function __construct(PDO $connection = null) { 
     parent::__construct($connection); 
    } 

    public function someFunction(){ 
     // access the pdo connection in the parent here: 
     $this->connection->..... 

    } 
}