无法检测会话变量是否存在 [英] Can't detect whether Session variable exists

问题描述

我正在尝试确定 Session 变量是否存在，但出现错误:

I'm trying to determine if a Session variable exists, but I'm getting the error:

System.NullReferenceException:对象引用未设置为对象的实例.

System.NullReferenceException: Object reference not set to an instance of an object.

代码:

    // Check if the "company_path" exists in the Session context
    if (System.Web.HttpContext.Current.Session["company_path"].ToString() != null)
    {
        // Session exists, set it
        company_path = System.Web.HttpContext.Current.Session["company_path"].ToString();
    }
    else
    {
        // Session doesn't exist, set it to the default
        company_path = "/reflex/SMD";
    }

那是因为 Session 名称"company_path"不存在，但我无法检测到它！

That is because the Session name "company_path" doesn't exist, but I can't detect it!

推荐答案

如果要检查Session ["company_path"]是否为空，请不要使用ToString().由于如果Session ["company_path"]为null，则Session ["company_path"].ToString()将给您例外.

Do not use ToString() if you want to check if Session["company_path"] is null. As if Session["company_path"] is null then Session["company_path"].ToString() will give you exception.

更改

if (System.Web.HttpContext.Current.Session["company_path"].ToString() != null)
{
    company_path = System.Web.HttpContext.Current.Session["company_path"].ToString();
}
else
{
    company_path = "/reflex/SMD";
}

收件人

if (System.Web.HttpContext.Current.Session["company_path"]!= null)
{
      company_path = System.Web.HttpContext.Current.Session["company_path"].ToString();
}
else
{
      company_path = "/reflex/SMD";
}

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