codeigniter ajax购物车更新量

class Cart extends CI_Controller {
    public function update_quantity() {
        $item_id = $this->input->post('item_id');
        $new_quantity = $this->input->post('new_quantity');

        // 更新数据库中的商品数量
        $this->load->model('cart_model');
        $this->cart_model->update_quantity($item_id, $new_quantity);

        // 返回更新后的购物车信息
        $cart_data = $this->cart_model->get_cart();
        echo json_encode($cart_data);
    }
}

class Cart_model extends CI_Model {
    public function update_quantity($item_id, $new_quantity) {
        $data = array(
            'quantity' => $new_quantity
        );
        $this->db->where('id', $item_id);
        $this->db->update('cart_items', $data);
    }

    public function get_cart() {
        // 获取购物车数据
        return $this->db->get('cart_items')->result_array();
    }
}

<script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
<script>
$(document).ready(function() {
    $('.update-quantity').on('change', function() {
        var item_id = $(this).data('item-id');
        var new_quantity = $(this).val();

        $.ajax({
            url: '<?php echo base_url("cart/update_quantity"); ?>',
            type: 'POST',
            data: { item_id: item_id, new_quantity: new_quantity },
            dataType: 'json',
            success: function(response) {
                // 更新页面上的购物车显示
                $('#cart-items').html(response);
            },
            error: function(xhr, status, error) {
                console.error("AJAX Error: " + status + error);
            }
        });
    });
});
</script>

<!-- 示例：更新购物车数量的输入框 -->
<input type="number" class="update-quantity" data-item-id="1" value="2">

header("Access-Control-Allow-Origin: *");
header("Access-Control-Allow-Methods: GET, POST, OPTIONS");
header("Access-Control-Allow-Headers: Content-Type");