加载没有会话pagetype的页面时出错 [英] Error in loading the page without session pagetype

问题描述

if (Session["Pagetype"].ToString() == "EXIST" || !String.IsNullOrEmpty(qID) || Session["Pagetype"].ToString() == "Preview")

对象引用未设置为对象的实例两个会话都出错类型。

"Object reference not set to an instance of an object" error for both session type.

if (Session["Pagetype"].ToString() == "EXIST" || Session["Pagetype"].ToString() == "Preview")

FYI - 页面未加载会话页面类型。所以会话状态为false。

FYI - the page is not loading from the session page type. so the session state is false.

推荐答案

object pageType = Session["Pagetype"];
if ((!string.IsNullOrEmpty(pageType.ToString()) && 
    (pageType.ToString() == "EXIST" || pageType.ToString() == "Preview")))
     || !String.IsNullOrEmpty(qID) 

可能发生的事情是Session [Pagetype]返回null并且因此你不能采用null对象的.ToString（）。你必须首先测试它为null



另一种写它的方式是

what is likely happening is that the Session["Pagetype"] is coming back null and as such you cannot take the .ToString() of a null object. you have to test it first for null

another way to write it is

object pageType = Session["Pagetype"];
if (!string.IsNullOrEmpty(pageType.ToString()))
{ 
    if (pageType.ToString() == "EXIST" || pageType.ToString() == "Preview"
     || !String.IsNullOrEmpty(qID)
    {
    }
}

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