Question

I have a very simple ASP.NET page that uploads an Excel workbook, then processes it. It uses AJAXFILEUPLOAD from the AJAX toolkit on ASP.NET… Here’s the markup:

<%@ Page Title="" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true"
CodeBehind="ImportWorkbook.aspx.cs" Inherits="Timesheet.ImportWorkbook" %>

<asp:Content ID="Content1" runat="server" ContentPlaceHolderID="HeaderContentPlaceHolder">
<h1 class="topContent">
    Upload CPAS Timesheet Workbooks
</h1>
</asp:Content>
<asp:Content ID="Content3" ContentPlaceHolderID="RightContentPlaceHolder" runat="server">
<br />
<br />
<asp:HiddenField ID="tbTSID" runat="server" />
<asp:HiddenField ID="tbWorkbookPath" runat="server" />
<ajaxToolkit:AjaxFileUpload ID="AjaxFileUpload1" runat="server" AllowedFileTypes="xls,xlsx,xlsm"
    CssClass="dropdown" MaximumNumberOfFiles="1" OnUploadComplete="AjaxFileUpload1_UploadComplete" />
<br />
<br />
<asp:Panel ID="ProcessChoices" runat="server" >
    <br />
    <br />
    <p>
        Select how you want this workbook processed:</p>
    <br />
    <asp:RadioButtonList ID="rbChoices" runat="server" BorderStyle="Groove" BorderWidth="2px"
        BorderColor="Black" BackColor="Teal" Font-Names="Tahoma" Font-Size="10pt" ForeColor="White"
        Width="40%">
        <asp:ListItem Value="True" Selected="True">&nbsp Replace ALL Items in the Timesheet</asp:ListItem>
        <asp:ListItem Value="False">&nbsp Add Items from this Workbook to the Existing Timesheet Items</asp:ListItem>
    </asp:RadioButtonList>
    <br />
    <br />
    <asp:Button ID="btnValidate" runat="server" Text="Validate and Process" 
        BackColor="#B92217" ForeColor="White" BorderColor="#7C1810" 
        BorderStyle="Groove" Font-Names="Tahoma" onclick="btnValidate_Click" />
</asp:Panel>
</asp:Content>
<asp:Content ID="Content4" ContentPlaceHolderID="BottomSpanContentPlaceHolder" runat="server">
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
</asp:Content>

The master page and css pages are trivial, formatting only.

Here’s the codebehind:

 using System;
using System.IO;
using TimesheetUtilites;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using AjaxControlToolkit;

    namespace Timesheet
    {

    public partial class ImportWorkbook : System.Web.UI.Page
    {
        private const string HDriveLocation= "H:\\mtv\\secure\\Construction\\Access\\CPAS WorkArea\\TimesheetUploads\\";
        private string strWorkbookPath;    
        private int currTSID;

        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                if (Request.QueryString["ID"] != null)
                {
                    tbTSID.Value = Request.QueryString["ID"];            // Storing the Timesheet ID in a hidden Textbox                    
                }
            }
            else
            {
                if (!string.IsNullOrEmpty(tbWorkbookPath.Value))
                {
                    ProcessChoices.Enabled = true;
                }
            }
            int.TryParse(tbTSID.Value, out currTSID);
            strWorkbookPath = tbWorkbookPath.Value;
        }
        protected void AjaxFileUpload1_UploadComplete(object sender, AjaxFileUploadEventArgs e)
        {
            strWorkbookPath = HDriveLocation + Path.GetFileName(e.FileName);
            tbWorkbookPath.Value = strWorkbookPath;
            AjaxFileUpload1.SaveAs(strWorkbookPath);
            ProcessChoices.Enabled = true;
        }

        protected void btnValidate_Click(object sender, EventArgs e)
        {
            bool processOption;
            bool.TryParse(rbChoices.SelectedValue, out processOption);
            strWorkbookPath = tbWorkbookPath.Value;
            TimesheetUtilites.ImportTimesheet imp = new ImportTimesheet(currTSID, strWorkbookPath, processOption);       
        }
    }
}

My issue is simple. Although the event handler “AjaxFileUpload1_UploadComplete” works fine, and uploads the file in an instant, when I fire the “btnValidate_Click” event, the “tbWorkbookPath.Value” has become an empty string, and the “ProcessChoices.Enabled” propety doesn’t change. Needless to say, the “Upload Complete” event handler is the only opportunity I have to capture this file path, so I’m at a loss what I’m doing wrong.

I posted on ASP.NET and go NO answers. Can anyone give me an idea where to start?

Answer 1

This is information you should be storing in your page’s ViewState so that it persists between postbacks and resets on page initialization. Change your private string member to something like the following:

private string strWorkbookPath {
    get {
        return this.ViewState["strWorkbookPath"];
    }
    set {
        this.ViewState["strWorkbookPath"] = value;
    }
}

If you need a primer on what the ViewState is, check out this article on MSDN: Saving Web Forms Page Values Using View State. It’s a bit dated but still communicates the basics of how ViewState operates currently.