ajax/php注释系统不工作

我有一个不太好用的注释系统。它将注释插入数据库，但仅在刷新页面后显示。我希望它在点击提交按钮后立即显示，并以滑动效果显示。

我怀疑是$arr[$k] = mysql_real_escape_string($v);造成了问题。我现在正在使用PDO，所以我知道它一定不存在，但当我将其删除到代码中时，它就停止工作了。

我的代码在下面。

<?php
    class Comment{
        private $data = array();
        public function __construct($row){
            $this->data = $row;
        }
        public function markup(){
            $d = &$this->data;
            $link_open = '';
            $link_close = '';
            if($d['url']){
                $link_open = '<a href="'.$d['url'].'">';
                $link_close =  '</a>';
            }
            $d['dt'] = strtotime($d['dt']);
            $url = 'http://'.dirname($_SERVER['SERVER_NAME'].$_SERVER["REQUEST_URI"]);
            return '
            <div class="comment">
                <div class="name">'.$link_open.$d['name'].$link_close.'</div>
                <div class="date" title="Added at '.date('H:i 'o'n d M Y',$d['dt']).'">'.date('d M Y',$d['dt']).'</div>
                <p>'.$d['body'].'</p>
            </div>
            ';
         }
         public static function validate(&$arr){
             $errors = array();
             $data  = array();
             if(!($data['email'] = filter_input(INPUT_POST,'email',FILTER_VALIDATE_EMAIL))){
                 $errors['email'] = '<div>Please insert your email</div>';
             }
             if(!($data['url'] = filter_input(INPUT_POST,'url',FILTER_VALIDATE_URL))){  
                 $url = '';
             }
             if(!($data['body'] = filter_input(INPUT_POST,'body',FILTER_CALLBACK,array('options'=>'Comment::validate_text')))){
                 $errors['body'] = '<div>Please type your comment</div>';
             }
             if(!($data['name'] = filter_input(INPUT_POST,'name',FILTER_CALLBACK,array('options'=>'Comment::validate_text')))){
                 $errors['name'] = '<div>Please insert your name</div>';
             }
             if(!empty($errors)){   
                 $arr = $errors;
                 return false;
             }
             foreach($data as $k=>$v){
                 $arr[$k] = mysql_real_escape_string($v);
             }
             $arr['email'] = strtolower(trim($arr['email']));
             return true;   
         }
         private static function validate_text($str){
             if(mb_strlen($str,'utf8')<1)
                 return false;
                 $str = nl2br(htmlspecialchars($str));
                 $str = str_replace(array(chr(10),chr(13)),'',$str);    
                 return $str;
         }
     }
 ?>

还有我的js文件：

<script>    
    $(document).ready(function(){
        var working = false;
        $('#addCommentForm').submit(function(e){
            e.preventDefault();
            if(working) return false;
                working = true;
                $('#submit').val('working');
                $('span.error').remove();
            $.post('commenting/submit.php',$(this).serialize(),function(msg){
            working = false;
            $('#submit').val('submit');
            if(msg.status){
        $(msg.html).hide().insertBefore('#addCommentContainer').slideDown();
                $('#body').val('');
            }else {
                $.each(msg.errors,function(k,v){
                    $('label[for='+k+']').append('<span class="error">'+v+'</span>');
                    });
                }
            },'json');
        });
    });
</script>