問題描述

我想使用 PDO 的 FETCH_INTO 的構(gòu)造函數(shù)填充類:

I want to populate class with constructor using FETCH_INTO of PDO:

class user
{
    private $db;
    private $name;

    function __construct($id)
    {
        $this->db = ...;

        $q = $this->db->prepare("SELECT name FROM users WHERE id = ?");
        $q->setFetchMode(PDO::FETCH_INTO, $this);
        $q->execute(array($id));

        echo $this->name;
    }
}

這不起作用.沒有錯(cuò)誤，只是沒有.腳本沒有錯(cuò)誤，FETCH_ASSOC 工作正常.

This does not work. No error, just nothing. Script has no errors, FETCH_ASSOC works fine.

FETCH_INTO 有什么問題?

推薦答案

您的代碼中有兩個(gè)錯(cuò)誤:

You have two errors in your code:

1) 你忘記了 $q->fetch()

1) You forgot $q->fetch()

 ...
 $q->execute(array($id));
 $q->fetch(); // This line is required

2) 但即使在添加 $q->fetch() 之后你也會(huì)得到這個(gè):

2) But even after adding $q->fetch() you'll get this:

致命錯(cuò)誤:無法訪問私有屬性 User::$name in ...

Fatal error: Cannot access private property User::$name in ...

因此，如您所見，即使在類方法內(nèi)部調(diào)用 PDO，它也無法訪問私有成員.

So, as you can see, PDO cannot access private members even if it is called inside class method.

這是我的解決方案:

...
$q->execute(array($id));
$q->setFetchMode(PDO::FETCH_ASSOC);
$data = $q->fetch();
foreach ($data as $propName => $propValue)
{
    // here you can add check if class property exists if you don't want to
    // add another properties with public visibility
    $this->{$propName} = $propValue;
}

這篇關(guān)于PDO 的 FETCH_INTO $這個(gè)類不起作用的文章就介紹到這了，希望我們推薦的答案對(duì)大家有所幫助，也希望大家多多支持html5模板網(wǎng)！