paging in GridView does not work with asynchronous calls

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Hello everyone,

Continuing my async calls I have it working in windows forms with Invoking the DataGridView.

When using async dataload and databind in ASP.NET I cannot invoke the GridView component directly.

When the next code is run:

C#

public partial class WebForm1 : System.Web.UI.Page
    {
       
        int pageNumber = 0;
        delegate void updateGridViewDelegate(DataTable aTable, int pageNumber);
        string query = "select top 100 * from [dbo].[FactInternetSales]";

        protected void Page_Load(object sender, EventArgs e)
        {
            if (!Page.IsPostBack)
            {
                DBConnecting.DataObjects.DataObjects src = new DBConnecting.DataObjects.DataObjects();
                src.ReturnDataTable += new DBConnecting.EventHandlers.DataTableEventArgs.DataTableEventHandler(HandleDataTable);
                src.AsyncDataTableStart(query, CommandType.Text);
            }
        }

        private void HandleDataTable(object sender, DataTableEventArgs e)
        {
           
            DataTable table = e.DataTableInfo;
            updateGridViewDelegate updDel = new updateGridViewDelegate(updateGridView);
            updDel.Invoke(e.DataTableInfo, pageNumber);
        }

        private void updateGridView(DataTable aTable, int pageNumber)
        {
            GridView1.DataSource = aTable;
            if (GridView1.AllowPaging)
                GridView1.PageIndex = pageNumber;

            GridView1.DataBind();
        }

        protected void GridView1_OPIC(object sender, GridViewPageEventArgs e)
        {
         
            pageNumber = e.NewPageIndex;
            DBConnecting.DataObjects.DataObjects src = new DBConnecting.DataObjects.DataObjects();
            src.ReturnDataTable += new DBConnecting.EventHandlers.DataTableEventArgs.DataTableEventHandler(HandleDataTable);
            src.AsyncDataTableStart(query, CommandType.Text);
        }
    }

the method GridView1_OPIC runs, the method HandleDataTable works and the method updateGridView works.
Still I only see page 1 of the gridview on screen. How to have the GridView updated in the webbrowser? An UpdatePanel is surronding the GridView in the aspx file.

aspx

<asp:UpdatePanel runat="server" ID="upnlDataGrid" >
        <ContentTemplate>
            <div id="grid">
                <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="true" AllowPaging="true" EnableSortingAndPagingCallbacks="true"
                    PageSize="20" OnPageIndexChanging="GridView1_OPIC">
                </asp:GridView>
            </div>
        </ContentTemplate>
    </asp:UpdatePanel>

When the UpdateMode is set to 'Conditional' the GridView1.Update() command runs fine the first time, but when paging the error given is:
'System.InvalidOperationException: The Update method can only be called on UpdatePanel with ID 'upnlDataGrid' before Render.'

How to overcome this problem?

Posted 30-Aug-11 9:35am

Herman<T>.Instance

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3 solutions

Solution 1

Please replace your html with below code

ASP.NET

<asp:UpdatePanel runat="server" ID="upnlDataGrid"     UpdateMode="Conditional">
        <contenttemplate>
            <div id="grid">
                <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="true" AllowPaging="true" EnableSortingAndPagingCallbacks="true"
                    PageSize="20" OnPageIndexChanging="GridView1_OPIC">
                
            </div>
        </contenttemplate>

And in your code behind please replace your updateGridView method with below code:

C#

private void updateGridView(DataTable aTable, int pageNumber)
       {
           GridView1.DataSource = aTable;
           if (GridView1.AllowPaging)
               GridView1.PageIndex = pageNumber;

           GridView1.DataBind();
           //update your update panel manually.
           upnlDataGrid.update();
       }

Hope it helped.

Posted 30-Aug-11 10:36am

Rupesh Kumar Tiwari

Updated 30-Aug-11 10:42am

v4

Comments

Herman<T>.Instance 31-Aug-11 3:37am

IF you would have read all the text you should have seen the last part about:
When the UpdateMode is set to 'Conditional' the GridView1.Update() command runs fine the first time, but when paging the error given is:
'System.InvalidOperationException: The Update method can only be called on UpdatePanel with ID 'upnlDataGrid' before Render.'

Herman<T>.Instance 31-Aug-11 8:24am

hoping/waiting for a good answer

Solution 3

i have same problem.please help.
Without master page,it work normally,but when using master page,it work only first time,second time does not work.please help how to fixed.

Posted 25-Nov-15 19:40pm

huuthai

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Herman<T>.Instance · Accepted Answer · 2011-09-01T10:37:00

Fixed it myself!
The problem was. While using the asynchronous model the page rendering was finished before the asynchronous call was finished. So when the result was there the page would have been submitted to the client!

You must use the polling model to fix this problem:
so my codebehind is now (and will be further perfectionized):

C#

public partial class WebForm1 : System.Web.UI.Page
    {
        bool finishedCall = false;
        int pageNumber = 0;
        delegate void updateGridViewDelegate(DataTable aTable, int pageNumber);
        string query = "select top 100 * from [dbo].[FactInternetSales]";

        protected void Page_Load(object sender, EventArgs e)
        {
            if (!Page.IsPostBack)
            {
                ShootTheCall();
            }
        }

        private void ShootTheCall()
        {
            DBConnecting.DataObjects.DataObjects src = new DBConnecting.DataObjects.DataObjects();
            src.ReturnDataTable += new DBConnecting.EventHandlers.DataTableEventArgs.DataTableEventHandler(HandleDataTable);
            src.AsyncDataTableStart(query, CommandType.Text);
        }

        private void HandleDataTable(object sender, DataTableEventArgs e)
        {
           
            DataTable table = e.DataTableInfo;
            updateGridViewDelegate updDel = new updateGridViewDelegate(updateGridView);
            updDel.Invoke(e.DataTableInfo, pageNumber);
        }

        private void updateGridView(DataTable aTable, int pageNumber)
        {
            GridView1.DataSource = aTable;
            if (GridView1.AllowPaging)
                GridView1.PageIndex = pageNumber;

            GridView1.DataBind();

            Label lblPageNr = (Label)Page.Master.FindControl("lblPageNr");
            if (lblPageNr != null)
                lblPageNr.Text = string.Format("PageNr set = {0}", pageNumber);

            finishedCall = true;
        }

        protected void GridView1_OPIC(object sender, GridViewPageEventArgs e)
        {
            pageNumber = e.NewPageIndex;
            ShootTheCall();
            while (!finishedCall)  // waiting till async call is finished
            {

            }
        }