对象引用未设置为对象的实例。（会话） [英] Object reference not set to an instance of an object.(Session)

问题描述

你好，



i我为会话变量创建一个属性

hello,

i am create a Property for session variable

public static string CurrentFolderPath
       {
           get { return System.Web.HttpContext.Current.Session["FolderPath"].ToString(); }
           set { System.Web.HttpContext.Current.Session["FolderPath"] = value; }
       }

但当我检查值时，它通过错误对象引用未设置为对象的实例

but when i am checking the value then it through error Object reference not set to an instance of an object

if (SessionManager.CurrentFolderPath != string.Empty)
              {
                  path = CommonFunctions.UserFolder;
              }

通过错误。请帮帮我如何检查此变量值。

it Through error. Please Help me How to Check This variable value.

推荐答案

您可能需要在物业的getter中添加空检查

you may need to add null check in getter of the property

public static string CurrentFolderPath
{
    get
    {
        if (HttpContext.Current.Session["FolderPath"] == null)
            return string.Empty;
        else
            return (string)HttpContext.Current.Session["FolderPath"];
    }

    set
    {
        HttpContext.Current.Session["FolderPath"] = value;
    }
}

旁注：要检查字符串为空，可以使用字符串.IsNullOrEmpty 方法

side note: to check string empty you can use string.IsNullOrEmpty method

if (!string.IsNullOrEmpty(SessionManager.CurrentFolderPath))
{
   path = CommonFunctions.UserFolder;
}

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