使用querrystring的asp.net Gridview [英] asp.net Gridview using querrystring

问题描述

您好，程序员，这里有几个问题.我在这部分 Label1.Text = Request.QueryString("CourseCatID").ToString 上遇到错误，提示Object reference not set to an instance of an object.，但是我认为我的语法是正确的.有任何想法吗?

Hello programmers, got a few question here. Im getting an error saying Object reference not set to an instance of an object. on this part Label1.Text = Request.QueryString("CourseCatID").ToString But I think my syntax is correct. Any Ideas?

<asp:TemplateField HeaderText="Edit">
    <ItemTemplate>
         <asp:LinkButton ID="LinkButton1" runat="server" PostBackUrl='<%#"CourseList.aspx?ID=" & Eval("CourseCatID")%>'  Text="Edit Courses"></asp:LinkButton>
   </ItemTemplate>
</asp:TemplateField>

已更新:
我认为我的requestquerystring不为null，因为ive在地址栏上收到了此消息
http://localhost:4543/Trainingplan/CourseList.aspx?ID=6

Updated:
I think my requestquerystring is not null since ive got this on address bar
http://localhost:4543/Trainingplan/CourseList.aspx?ID=6

推荐答案

确保Request.QueryString("CourseCatID")不为null.
如果是，则在null上的ToString()会引发您得到的错误.

如果您需要有关将多个值传递给超链接字段的更多信息，请参见此处 [ ^ ].

Make sure that Request.QueryString("CourseCatID") is not null.
If it is, then a ToString() on null will throw the error you are getting.

If you need more information on passing multiple values to a hyperlink field, see here[^].

ur通过PostBackUrl =''<％#"CourseList.aspx?ID ="&Eval("CourseCatID")％>因此请使用Request.QueryString("ID").ToString

ur passing PostBackUrl=''<%#"CourseList.aspx?ID=" & Eval("CourseCatID")%> so use Request.QueryString("ID").ToString

<asp:linkbutton id="lnkEdit" postbackurl="<%# "CourseList.aspx?ID=" + Eval("ID")%>" text="Edit Courses" runat="server" xmlns:asp="#unknown"></asp:linkbutton>

并在重定向页面中意味着在CourseList.aspx页面上
像
一样检查

and in redirected page means on CourseList.aspx page
check like

string id = Request.QueryString["ID"].ToString();

if(id != "" or id != null)
{
    //do your code for what you whant that id.
}

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