Using variable from code behind in ASP.NET

I'm having a bit of difficulty setting a variable from the code behind and utilising it in the ASP.NET page (setting it as the value inside a textbox). My webpage simply errors and says it does not exist in the current context. The variable is declared and set all in the Page_Load method.

Here is the relevant ASP.NET code. I assume you will not need to see the code behind, as I have tested outputting the variable via the codebehind (using Response.Write) and that works fine.

 <asp:TemplateField HeaderText="Initial Path" 
                SortExpression="Initial_Path">
                <EditItemTemplate>
                    <asp:TextBox ID="TextBox6" runat="server" 
                        Text='<%# initialPath %>'></asp:TextBox>
                </EditItemTemplate>
                <InsertItemTemplate>
                    <asp:TextBox ID="TextBox8" runat="server" 
                        Text='<%# initialPath %>'></asp:TextBox>
                </InsertItemTemplate>
                <ItemTemplate>
                    <asp:Label ID="Label8" runat="server" Text='<%# initialPath %>'></asp:Label>
                </ItemTemplate>
            </asp:TemplateField>

Thanks :)

EDIT: Ok sure, here's the relevant parts of the code behind

       string schedID = sched.SchedulerInstanceId;
        JobDetail jobDetail2 = sched.GetJobDetail(Request.QueryString["JOB_NAME"], "sched1");
        JobDataMap dataMap2 = jobDetail2.JobDataMap;
        initialPath = dataMap2.GetString("开发者_运维知识库initialPath");
        Response.Write(initialPath);

The response.write is for debugging - it outputs the variable correctly so the variable is actually set

EDIT 2: Here is the code behind

public partial class EditJobDetails : System.Web.UI.Page
    {
    public string initialPath { get; set; }

    protected void Page_Load(object sender, EventArgs e)
    {

        //Scheduler stuff for Quartz.NET, removed because of length

        string schedID = sched.SchedulerInstanceId;
        JobDetail jobDetail2 = sched.GetJobDetail(Request.QueryString["JOB_NAME"], "sched1");
        JobDataMap dataMap2 = jobDetail2.JobDataMap;
        initialPath = dataMap2.GetString("initialPath");
    }

What's not working is just the <%= initialpath %> in the ASP form. It simply just doesn't show anything, like the variable is assigned nothing

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In the codebehind you need to create it as a public property. Then you can use it all you want in the aspx page.

in code behind:

public string yourvar { get; set; }

in aspx:

    <EditItemTemplate>
        <asp:TextBox ID="TextBox6" runat="server" 
            Text='<%= yourvar %>'></asp:TextBox>
    </EditItemTemplate>

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What I don't see here is where the call to DataBind() is made. If it's made before is set then <%#initialPath%> will write its starting value (null, which gets written as an empty string in such a case). If it's not made at all, then <%#initialPath%> will never write anything. You need to make sure DataBind() is called at an appropriate time, such as at the end of Page_Load

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<%# initialPath %> is a databinding expression meaning that ASP.NET will look for a initialPath property on the collection you are binding to. Obviously such property doesn't exist as this is a local variable.