If you set AllowPaging="true" or AllowSorting="true" on a GridView control without using a DataSourceControl DataSource (i.e. SqlDataSource, ObjectDataSource), you will run into the following errors:

When changing the page on the GridView control:

The GridView 'GridViewID' fired event PageIndexChanging which wasn't handled.

When clicking a column name to sort the column on the GridView control:

The GridView 'GridViewID' fired event Sorting which wasn't handled.

As a result of not setting the DataSourceID property of the GridView to a DataSourceControl DataSource, you have to add event handlers for sorting and paging.

<asp:GridView ID="gridView" OnPageIndexChanging="gridView_PageIndexChanging" OnSorting="gridView_Sorting" runat="server" />

private string ConvertSortDirectionToSql(SortDirection sortDireciton)
{
   string newSortDirection = String.Empty;

   switch (sortDirection)
   {
      case SortDirection.Ascending:
         newSortDirection = "ASC";
         break;

      case SortDirection.Descending:
         newSortDirection = "DESC";
         break;
   }

   return newSortDirection
}

protected void gridView_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
   gridView.PageIndex = e.NewPageIndex;
   gridView.DataBind();
}

protected void gridView_Sorting(object sender, GridViewSortEventArgs e)
{
   DataTable dataTable = gridView.DataSource as DataTable;

   if (dataTable != null)
   {
      DataView dataView = new DataView(dataTable);
      dataView.Sort = e.SortExpression + " " + ConvertSortDirectionToSql(e.SortDirection);

      gridView.DataSource = dataView;
      gridView.DataBind();
   }
}

StrongTypes wrote:

protected void gridView_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
   gridView.PageIndex = e.NewPageIndex;
   gridView.DataBind();
}

protected void gridView_PageIndexChanging(object sender, GridViewPageEventArgs e)
{

   // Add here your method for DataBinding
   BindGridControl();

   gridView.PageIndex = e.NewPageIndex;
   gridView.DataBind();
}

ChrisOngsuco wrote:

protected void gridView_PageIndexChanging(object sender, GridViewPageEventArgs e)
{

   // Add here your method for DataBinding
   BindGridControl();

   gridView.PageIndex = e.NewPageIndex;
   gridView.DataBind();
}

Without the databinding method you won't get the paged result.

I've used that code as-is (the code in my original post), and it works perfectly. No need for a custom method.

The more that I think of it, you would need a method only if you want to ensure that the displayed data is fresh and not stale from the current data source. However, this does bring up the downside to interface paging, which is filling the entire data source (i.e. DataTable, DataSet) each time you do that, which can get expensive depending on the amount of rows returned.

Hi,

The paging function works for me but no the sorting one.  It always fails at this line:

if (m_DataTable != null)

because m_DataTable is always NULL according to the VS Debugger.  Does anyone have any ideas on I can get this to work?

Thanks a lot!

What are you using as a data source (i.e. DataTable, DataSet, etc.) to bind to the GridView?

Thanks a lot!. I  was using dataset to bind my GridView control instead of dataTable.  I changed to use DataTable and now it works. 

Another problem I am having is that after sorting, different data gets displayed on the current screen since now they are in different order - I am also using pagination on these pages.  There are anyway to make sort just the current page or after clicking on sort, the same data displays on the current screen sorted?

Can you please explain a little further.  I used a DataTable to bind to my grid. 

gvResults.DataSource = ds.Tables[0];

gvResults.DataBind();

That worked fine, however the only way I was able to make the sort work using your example I had to hold onto the datasource via  ViewState

ViewState["gvResults_DataSource"] = gvResults.DataSource;

After having done that I was able to modify the first line of the sorting routine to

DataTable dt = (DataTable)ViewState["gvResults_DataSource"];

The sort worked after that.  How did you avoid having to use ViewState.  I'm fairly new at this but I'm worried about a performance problem if there are a large number of records.

Thanks in advance.

You shouldn't have to put it in ViewState. Revert back to the following, but add the first line that I have below and let me know what the output it produces is:

protected void gridView_Sorting(object sender, GridViewSortEventArgs e)
{
   Response.Write(gridView.DataSource.GetType()); //Add this line

   DataTable m_DataTable = gridView.DataSource as DataTable;

   if (m_DataTable != null)
   {
      DataView m_DataView = new DataView(m_DataTable);
      m_DataView.Sort = e.SortExpression + " " + ConvertSortDirectionToSql(e.SortDirection);

      gridView.DataSource = m_DataView;
      gridView.DataBind();
   }
}

I added the following code:

robbyram wrote:

 One question though, for some reason my sort direction seems to always be ascending.  I thought it was supposed to automatically toggle back and forth.

Thanks for catching that. It was something I overlooked originally. Like with the DataGrid, you'll have to place it in the ViewState to get that to work. I'll update that code tonight so ascending/descending sort works in both directions.

I also find that the GridView.DataSource is Nothing in the GridView Sorting event.  I'm using a DataTable as the DataSource in the Page Load event.

Is this because Sorting fires before DataBound?  Also, why does this work for the original poster of this code?  Is he secretly storing the DataTable somewhere and not telling us?

Hi Mike,

The code does work and I'll be posting a live working example with source code in about 1/2 hour.

Ryan

Here's the live working example with source code: GridView Sorting/Paging w/o a DataSourceControl DataSource

I had to tweak the code a little to make sorting work in both directions.

Enjoy.
Ryan

Ok, I see what the difference is.  Since your call to PopulatePublishersGridView()
is not inside a "if (!Page.IsPostBack)", you are creating a DataTable object and Filling it from the database on every postback.  That's why you have the GridView.DataSource available in the Sorting event.  The Page_Load event is populating the GridView.DataSource before the Sorting event fires.

Thanks for posting your code.

Hi Lisa,

I'll publish a VB.NET version of the live working C# code sometime tonight.

Ryan

Here's the VB.NET version: GridView Sorting/Paging w/o a DataSourceControl DataSource

HTH,
Ryan