在 ASP.NET 的 Web 应用程序中使用多个 cookie

Question

我的网络应用程序中有 cookie 来存储用户语言。 我在

中创建了这个cookie

Application_BeginRequest && Application_Start

在我的 global.asax 文件中使用此代码：

Response.Cookies["IPortalCookies"]["Language"] = "en";
                        Response.Cookies["IPortalCookies"]["Direction"] = "ltr";
                        Response.Cookies["IPortalCookies"].Expires = DateTime.Now.AddYears(1);

现在我需要为每个用户创建另一个 cookie 来存储喜欢：

int articleid = Convert.ToInt32(e.CommandArgument);
        //    var _ah = new ArticlesHelper();
        //    if (Request.Cookies["IPortalCookies"] != null)
        //    {
        //        if (Request.Cookies["IPortalCookies"]["Likes"] == null || Request.Cookies["IPortalCookies"]["Likes"].Contains("'" + articleid + "'") == false)
        //        {
        //            if (_ah.LikeIt(articleid))
        //            {
        //                Response.Cookies["IPortalCookies"]["Likes"] = Request.Cookies["IPortalCookies"]["Likes"] + ",'" + articleid + "'";
        //                BindRepeater();
        //            }
        //        }
        //    }

但是当点赞 cookie 创建其他 cookie 时会消失，我会得到这个错误：

String reference not set to an instance of a String.
Parameter name: name

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.ArgumentNullException: String reference not set to an instance of a String.
Parameter name: name

Source Error: 

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace: 


[ArgumentNullException: String reference not set to an instance of a String.
Parameter name: name]
   System.Globalization.CultureInfo..ctor(String name, Boolean useUserOverride) +14174389
   PortalCore.Global.Application_BeginRequest(Object sender, EventArgs e) +1093
   System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +80
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +165

Answer 1

我不知道是哪一行抛出了这个错误

但是我猜下面一行会出错

if (Request.Cookies["IPortalCookies"]["Likes"] == null || Request.Cookies["IPortalCookies"]["Likes"].Contains("'" + articleid + "'") == false)
        //        {
        //            if (_ah.LikeIt(articleid))
        //            {
        //                Response.Cookies["IPortalCookies"]["Likes"] = Request.Cookies["IPortalCookies"]["Likes"] + ",'" + articleid + "'";
        //                BindRepeater();
        //            }
        //        }

你需要检查不等于null

Request.Cookies["IPortalCookies"]["Likes"] != null

在尝试获取 cookie 的值之前，您应该确保 cookie 存在；如果 cookie 不存在，你会得到一个 NullReferenceException 异常。