jQuery select2返回json

Question

Hi there using the jquery select2-plugin in this context:

$(document).ready(function () {
    $('#dropdown_users').select2({ 
        placeholder: "Search User", 
        minimumInputLength: 2, 
        multiple: false, 
        ajax: { 
            url: "search.php", 
            dataType: 'json', 
            quietMillis: 100, 
            data: function (term, page) {
                return {
                    q: term, 
                    page_limit: 10 
                };
            },
            results: function (data, page) {
                return {
                    results: data
                };
            }
        }
    });
});

<input type="hidden" id="dropdown_users" />

and this search.php:

include "storescripts/connect_to_mysql.php";

$data = trim(strip_tags($_GET['data']));

if(!empty($data) && isset($data) && strlen($data) != 0) {
    $stmt = $dbh->prepare('SELECT product FROM `table` WHERE `product` LIKE :keyword');
    $keyword = "%".$data."%";
    $stmt->bindParam(':keyword', $keyword, PDO::PARAM_STR);
    $stmt->execute();   
    while ($user = $stmt->fetch(PDO::FETCH_ASSOC)) {
        $user['data']=htmlentities(stripslashes($user['product']));
        $user_set[] = $user;
    }
    echo json_encode($user_set);
} else {                      
    $user_set[] = array("result" => 0 , "text" => "You forgot to type!");
}
echo json_encode($user_set);  

Every time i get in my console:

[{"result":0,"text":"You forgot to type!"}]

Even if I type more than two characters I get this message in my console. Anybody could help with this issue? Greetings!!