如何在asp.net razor视图中显示自定义错误

如果数据库中不存在用户ID，我想显示“找不到配置文件”消息。我如何实现它。下面的代码不起作用

          UserId = Request.QueryString["UserId"];
           var db = Database.Open("mystring");
           var selectCommand = "SELECT * FROM UserProfile WHERE UserId = @0";
           var row = db.QuerySingle(selectCommand, UserId);

             if (row != null)
            {
                Email = row.Email;
                fullname = row.fullname;
                about = row.about;
             }else{
                 ModelState.AddFormError("No Profile Found.");

             }

试着这样做：

@{
    var userId = Request.QueryString["UserId"];
    var db = Database.Open("mystring");
    var selectCommand = "SELECT * FROM UserProfile WHERE UserId = @0";
    var row = db.QuerySingle(selectCommand, UserId);
}

@if (row != null) {
    <div>
        Email: @row.Email
    </div>
    <div>
        Fullname: @row.fullname
    </div>
    <div>
        About: @row.about
    </div>
} else {
    <div>No Profile Found.</div>
}

@{
var userId=Request.QueryString[“userId”]；
var db=Database.Open（“mystring”）；
var selectCommand=“从UserProfile中选择*，其中UserId=@0”；
var row=db.QuerySingle（selectCommand，UserId）；
}
@如果（行！=null）{
电子邮件：@row.Email
全名：@row.Fullname
About:@row.About
}否则{
找不到配置文件。
}