Paging in Gridview, can't access another page

Question

I have a web app where everytime I upload an Excel file, its contents appears in Gridview, which is binded with a DataTable. Using the properties, I have set paging and sorting to true.

When I input a file using fileupload and a submit button, the web app has page numbers at the bottom appear. It also correctly sorts it, (my page size is set to 10), however, when i click on the next page (pg 2, for instance), nothing shows up until i upload the another file and hit submit again.

This is the code in which I build the table:

protected void AddResultToGrid(String url, String result)
{
  data = (DataTable)Session["URLSessionData"];
  DataRow dr = data.NewRow();
  dr[0] = url;
  dr[1] = result;
  data.Rows.Add(dr);

  gdvResults.DataSource = data;
  gdvResults.DataBind();
  Session["URLSessionData"] = data;
}

This is the page load:

protected void Page_Load(object sender, EventArgs e)
{
  lblFiup.Text = "";

    data.Columns.Add("URL", typeof(String));
    data.Columns.Add("Status", typeof(String));
    gdvResults.DataSource = data;
    gdvResults.DataBind();

  gdvResults.AllowPaging = true;
  gdvResults.AllowSorting = true;
  if (!Page.IsPostBack)
  {

    Session["URLSessionData"] = data;
  }
}

I think it may have something to do with the page index... but i'm not sure. Here's my page index change method:

    protected void gdvResults_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {

        e.NewPageIndex = e.NewPageIndex + 1;
        DataBind();

    }

Thanks in advance for your help (:

Answer 1

I had the same problem. To handle this, try setting the page index in the PageIndexChange event like so:

protected void gdvResults_PageIndexChanging(object sender, GridViewPageEventArgs e) 
{ 

    gdvResults.PageIndex = e.NewPageIndex; 
    gdvResults.EditIndex = -1;
    DataBind(); 

}

Setting EditIndex is only needed if you will be using edit mode to update values. Otherwise you can exclude that.

Good Luck. Hope this helps :)

---

I've stripped my program to do nothing but fill the gridview and allow page changing.

namespace EorManager
{
public partial class _Default : System.Web.UI.Page
{
    //Connection to database
    EorLinqClassDataContext eorConnection = new EorLinqClassDataContext();

    protected void Page_Load(object sender, EventArgs e)
    {
        //On FIRST page load I call my BindGridview method. 
        //Afterward I only call my BindGridview method from events
        if (!IsPostBack)
        {
            BindGridview();
        }
    }

    private void BindGridview()
    {
        //This is where I pull three columns from a table which I want displayed in the gridview. 
        //You will want to upload your excel file in a seperate method and save it locally so you dont have to constantly re-upload it
        var myGridDataSource = from p in eorConnection.EORCategories
                               orderby p.EORCategoryID
                               select new
                               {
                                   EORCategoryID = p.EORCategoryID,
                                   EOR = p.EOR,
                                   CategoryName = p.CategoryName
                               };


        grdEOR.DataSource = myGridDataSource;
        grdEOR.DataBind();

    }

    protected void grdEor_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        grdEOR.PageIndex = e.NewPageIndex;
        BindGridview();

    }
}
}

Answer 2

    public partial class _Event : System.Web.UI.Page
    {
        public HttpWebRequest req;
        public HttpWebResponse resp;
        public String link;
        public String line;
        public String stat;
        public String result;
        public DataTable data = new DataTable();
        public DataTable clrdata = new DataTable();

        protected void Page_Load(object sender, EventArgs e)
        {
            lblFiup.Text = "";
            if (!Page.IsPostBack)
            {                
                data.Columns.Add("URL", typeof(String));
                data.Columns.Add("Status", typeof(String));
                AddResultToGrid("", ""); // this is the only way i know how to do this, as of now...
                data.Rows[0].Delete();

                 Session["URLSessionData"] = data;
                BindGridView();

            }
        }

        private void BindGridView()
        {
            gdvResults.DataSource = data;
            gdvResults.DataBind();
        }

        protected void AddResultToGrid(String url, String result)
        {
            data = (DataTable)Session["URLSessionData"];
            DataRow dr = data.NewRow();
            dr[0] = url;
            dr[1] = result;
            data.Rows.Add(dr);

            gdvResults.DataSource = data;
            gdvResults.AllowPaging = true;
            gdvResults.DataBind();
            Session["URLSessionData"] = data;
        }

Answer 3

Ok, I made a mock datatable for my program. It acted just like you described. the second page was always blank. I set the DataTable to static and it worked. Here's my final code:

namespace EorManager
{
public partial class _Default : System.Web.UI.Page
{
    //Must be static
    static DataTable data = new DataTable();

    protected void Page_Load(object sender, EventArgs e)
    {
        //On FIRST page load I call my BindGridview method. 
        //Afterward I only call my BindGridview method from events
        if (!IsPostBack)
        {
            //make a column
            DataColumn myDataColumn = new DataColumn();
            myDataColumn.DataType = Type.GetType("System.String");
            myDataColumn.ColumnName = "url";
            data.Columns.Add(myDataColumn);

            //add rows
            DataRow row;
            row = data.NewRow();
            row["url"] = "www.google.com";
            data.Rows.Add(row);
            row = data.NewRow();
            row["url"] = "www.facebook.com";
            data.Rows.Add(row);
            row = data.NewRow();
            row["url"] = "www.stackoverflow.com";
            data.Rows.Add(row);
            row = data.NewRow();
            row["url"] = "www.google.com";
            data.Rows.Add(row);
            row = data.NewRow();
            row["url"] = "www.facebook.com";
            data.Rows.Add(row);
            row = data.NewRow();
            row["url"] = "www.stackoverflow.com";
            data.Rows.Add(row);
            row = data.NewRow();
            row["url"] = "www.google.com";
            data.Rows.Add(row);
            row = data.NewRow();
            row["url"] = "www.facebook.com";
            data.Rows.Add(row);
            row = data.NewRow();
            row["url"] = "www.stackoverflow.com";
            data.Rows.Add(row);
            row = data.NewRow();
            row["url"] = "www.google.com";
            data.Rows.Add(row);
            row = data.NewRow();
            row["url"] = "www.facebook.com";
            data.Rows.Add(row);
            row = data.NewRow();
            row["url"] = "www.stackoverflow.com";
            data.Rows.Add(row);
            row = data.NewRow();
            row["url"] = "www.google.com";
            data.Rows.Add(row);
            row = data.NewRow();
            row["url"] = "www.facebook.com";
            data.Rows.Add(row);
            row = data.NewRow();
            row["url"] = "www.stackoverflow.com";
            data.Rows.Add(row);
            row = data.NewRow();
            row["url"] = "www.google.com";
            data.Rows.Add(row);
            row = data.NewRow();
            row["url"] = "www.facebook.com";
            data.Rows.Add(row);
            row = data.NewRow();
            row["url"] = "www.stackoverflow.com";
            data.Rows.Add(row);
            row = data.NewRow();
            row["url"] = "www.google.com";
            data.Rows.Add(row);
            row = data.NewRow();
            row["url"] = "www.facebook.com";
            data.Rows.Add(row);
            row = data.NewRow();
            row["url"] = "www.stackoverflow.com";
            data.Rows.Add(row);


            BindGridview();
        }
    }


    private void BindGridview()
    {

        grdEOR.DataSource = data;
        grdEOR.DataBind();

    }

    protected void grdEor_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        grdEOR.PageIndex = e.NewPageIndex;
        BindGridview();

    }
}
}

This is my GridView code:

<asp:GridView ID="grdEOR" runat="server" BackColor="White"
            BorderColor="#999999" OnPageIndexChanging="grdEor_PageIndexChanging"
            BorderStyle="Solid" BorderWidth="1px" CellPadding="3" ForeColor="Black" GridLines="Vertical"
            AllowPaging="True"
            PageSize="15" 
                                          >
            <PagerSettings Mode="NumericFirstLast" />
            <FooterStyle BackColor="#CCCCCC" />
            <PagerStyle BackColor="#999999" ForeColor="Black" HorizontalAlign="Center" />
            <SelectedRowStyle BackColor="#000099" Font-Bold="True" ForeColor="White" />
            <HeaderStyle BackColor="Black" Font-Bold="True" ForeColor="White" />
                        <EditRowStyle BackColor="#2D41F7" />
            <AlternatingRowStyle BackColor="#CCCCCC" BorderColor="Black" 
                BorderStyle="Solid" BorderWidth="5px" />
        </asp:GridView>