php - 如何在 __construct() 中创建 PDO 连接？

Question

我有一个包含三个方法的类。所有这些方法都需要数据库，然后我想在一切之前创建一个连接数据库的系统。像这样:

Class myclass
{
    private $db;

    public function __construct() {

        $db = new PDO("mysql:host = hostname; dbname = database",username, password);
    }

    function one()   {/* it needs to database and I will use it like this: */
                         $this->$db->prepare("select ...");
                     }
    function two()   {/* also it needs to database */}
    function three() {/* also it needs to database */}
}

现在我想知道(首先)我所做的是一种标准方法吗？和(第二)我如何检查[如果连接断开(换句话说连接不存在)然后连接]？

Answer 1

要访问类属性，您必须使用 -> 语法:

Class myclass
{
    private $db;

    public function __construct() {

        $this->db = new PDO("mysql:host = hostname; dbname = database",username, password);
    }

    function one()   {/* it needs to database and I will use it like this: */
        $this->db->prepare("select ...");
    }
    function two()   {/* also it needs to database */}
    function three() {/* also it needs to database */}
}

如果你想检测错误，启用错误信号

$this->db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

并在使用数据库的代码周围使用try/catch:

function one() {
    try {
        $this->db->prepare(...);
    } catch (PDOException $e) {
        // handle error
    }
}