Pass mysqli object to class
<p>I want to pass a mysqli object to a class. I create the object in one file:</p>

<pre><code>$host = 'host';
$user = 'username';
$pw = 'pw';
$db = 'db';

$link = new mysqli($host,$user,$pw,$db);
</code></pre>

<p>which is included in one page:</p>

<pre><code>include 'php/mysql.php';
include 'php/classes/Class.Dataconnector.php';
$dc = new Dataconnector($link);
</code></pre>

<p>and the class looks like this:</p>

<pre><code>class Dataconnector {
    protected $_link;
    protected $_stub;

    function __construct(mysqli $link) {
        $_link = $link;
    }

    public function getPageContent($stub) {
        $query = "select * from contents where pageId = (select id from pages where stub = '$stub')";
        $result = mysqli_query($_link,$query);
        return $result;
    }
}
</code></pre>

<p>But I get this error:</p>

<pre><code>Warning: mysqli_query() expects parameter 1 to be mysqli, null given in \php\classes\Class.Dataconnector.php on line 18
</code></pre>

<p>What is wrong ?</p>
