Re: I lose data, when I try to save a loaded DataTable on the click of another button in an asp.net webform

The reason for this is that your instance is not maintained between calls. You are better off getting the data source from the GridView1 (assuming that you are using viewstate, but that will be VERY expensive in terms of how much data you are moving across the wire) and then working with that on the save.

Or, you could store the data table in the session, and retrieve it when saving.


--
- Nicholas Paldino [.NET/C# MVP]
- mvp@xxxxxxxxxxxxxxxxxxxxxxxxxxx

<chike_oji@xxxxxxxxx> wrote in message news:e953a227-1d07-43f8-9b12-527bae4a790e@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Please can someone help me. I am writing a web application,
that allows for the upload of an excel *** into the database.
I have an upload button and a save button.

The upload button allows for the retrieval of the excel data into
a DataTable, which is bound to a GridView for previewing before
saving to the Database.

But, whenever I click on the save button, I lose the DataTable's data,
so I lose the data I want to save to the database.

I am using .net framework 2.0, vs2005 professional, win xp
professional
and below is the codebehind file for the page.

Thanks in advance.

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using IConceptDBWebUpdate.BLL;

public partial class _Default : System.Web.UI.Page
{
DataTable dtData = null;

public string UploadID
{
get
{
return (ViewState["UploadID"] != null) ?
ViewState["UploadID"].ToString() : string.Empty;
}
set
{
ViewState["UploadID"] = value;
}
}

protected void Page_Load(object sender, EventArgs e)
{
//GridView1.DataSource =
IConceptDBWebUpdate.BLL.StockDetail.GetAllStockDetails();
//GridView1.DataBind();
}
protected void Upload_Click(object sender, EventArgs e)
{
//DataTable dtData = null;


if (IsValid)
{
UploadID = Guid.NewGuid().ToString();
string path = string.Format("{0}\\{1}.xls",
ConfigurationManager.AppSettings["ExcelFilePath"], UploadID);

try
{

if (UploadExcel.PostedFile == null)
{
throw new Exception("Please select a File to
upload");
}
UploadExcel.PostedFile.SaveAs(path);
//Create query to be passed to the Excel conversion
method.
string sql = "Select * from [stockdetails$]";
//Store data from Excel file in a DataTable
dtData =
MicrosoftExcelClient.ConvertExcelToDataTable(path, sql);
//Bind the GridView to the DataTable to display the
data
GridView1.DataSource = dtData;
GridView1.DataBind();
//TODO: Delete all data in the current stockdetails
table
Upload.Visible = false;
btnSave.Visible = true;
//UploadExcel.Enabled = false;

}
catch (Exception ex)
{
Message.CssClass = "ErrorMessage";
string error = ex.Message.Replace("\n", "<br>");

Message.Text = String.Format("The following error
occured:<BR>{0}", error);
}
finally
{
System.IO.File.Delete(path);
}
}//End of IsValid check
}
protected void Cancel_Click(object sender, EventArgs e)
{

}




protected void btnSave_Click(object sender, EventArgs e)
{
//if (!Page.IsPostBack)
//{

//Loop through the DataTable and add the rows to the
Database table stockdetails.
foreach (DataRow row in dtData.Rows)
{
string company = row["company"].ToString();
string keyword = row["keyword"].ToString();
string stockprice = row["stockprice"].ToString();
string stockworth = row["stockworth"].ToString();
StockDetail.InsertStockDetails(company, keyword,
stockprice, stockworth);

}
//Database update complete.
Message.Text = String.Format("The Database has now been
updated.<BR>");

GridView1.Enabled = false;
//UploadExcel.Enabled = true;

//}//End of IsPostBack block
}
}

.