问PHP在mysql中插入json对象发布的数据

EN

function getItems()
{ 
        var listview_array = new Array();
        $( "#itemList li" ).each(function(index) {
            listview_el = new Object();
            listview_el.id = index;
            listview_el.name=$(this).text();
            listview_el.owner="owner";
            listview_array.push(listview_el);
        });
        var stringifyObject = JSON.stringify(listview_array);
        //alert(stringifyObject);
        $.ajax({
            type: "POST",
            dataType: 'json',
            url: "insert.php",
            data: { mydata: stringifyObject },
        });
        //showItems();

}

 <?php

    $con = new mysqli($servername, $username, $password, $dbname);
    if (!$con) {
      die('Could not connect: ' . mysqli_error($con));
    }

    echo "preps";
    if($preparedStatement = $con->prepare('INSERT INTO Einkaufsliste (item, owner) VALUES (:name, :owner)')){
        $preparedStatement->execute(json_decode($_POST["mydata"], true));
        $preparedStatement->close();
        echo "done";
    };

    $con->close();
    ?>