ASP.NET 4.5 GridView: PostBack of last page

Question 1

As I was not satisfied with my proposed solution (brought too many issues for future development), I have decided to go the "Control development" way to ensure everything is created correctly. It occurs no matter the type of PagerTemplate I am using - I am using one, the postback does not fire from Last page. Hopefully I am not the only one :-)

For those who are experiencing the same issues, I am providing custom control that works OK (of course, does not implement PagerSettings and PagerTemplates, but brings the basic functionality).

public class ExtendedGridView : System.Web.UI.WebControls.GridView
{
    protected override void InitializePager(System.Web.UI.WebControls.GridViewRow row, int columnSpan, System.Web.UI.WebControls.PagedDataSource pagedDataSource)
    {
        HtmlGenericControl ul = new HtmlGenericControl("ul");

        ul.Attributes.Add("class", "pagination pull-right");

        AddPager(ul, commandArgument: "First", text: "<span class='glyphicon glyphicon-fast-backward'></span>");

        for (int i = 0; i < PageCount; i++)
        {
            AddPager(ul, i);
        }

        AddPager(ul, commandArgument: "Last", text: "<span class='glyphicon glyphicon-fast-forward'></span>");

        row.CssClass = "table-footer";
        row.Cells.Add(new System.Web.UI.WebControls.TableCell());
        row.Cells[0].ColumnSpan = columnSpan;
        row.Cells[0].Controls.AddAt(0, ul);            
    }

    protected virtual void navigate_Click(object sender, EventArgs e)
    {
        string commandArgument = ((System.Web.UI.WebControls.LinkButton)sender).CommandArgument.ToString();
        int pageIndex = 0;

        if (!int.TryParse(commandArgument, out pageIndex)) {
            switch (commandArgument)
            {
                case "First": pageIndex = 0; break;
                case "Last": pageIndex = PageCount - 1; break;
                case "Prev": pageIndex = PageIndex - 1; break;
                case "Next": pageIndex = PageIndex + 1; break;
            }
        }

        OnPageIndexChanging(new System.Web.UI.WebControls.GridViewPageEventArgs(pageIndex));
    }

    private void AddPager(System.Web.UI.Control parentControl, int pageIndex = -1, string commandArgument = null, string text = null)
    {
        HtmlGenericControl li = new HtmlGenericControl("li");

        if (pageIndex == PageIndex)
            li.Attributes.Add("class", "active");

        System.Web.UI.WebControls.LinkButton button = new System.Web.UI.WebControls.LinkButton();
        button.CommandName = "Page";

        if (text == null)
            button.Text = (pageIndex + 1).ToString();
        else
            button.Text = text;

        if (string.IsNullOrWhiteSpace(commandArgument))
            button.CommandArgument = string.Format("{0}", pageIndex);
        else
            button.CommandArgument = commandArgument;

        button.Click += navigate_Click;

        li.Controls.Add(button);
        parentControl.Controls.Add(li);
    }
}

Just make sure your markup is: - AllowPaging="true" - AllowCustomPaging="false" - PageSize="whatever" - and you still provide VirtualItemCount in code behind

Code behind using SelectMethod could be like this:

protected void Page_Load(object sender, EventArgs e)
{

}

public IEnumerable SearchResults_GetData(int startRowIndex, int maximumRows, out int totalRowCount, string sortByExpression)
{
    int pageIndex = (int)(startRowIndex / maximumRows);
    return Membership.GetAllUsers(pageIndex, maximumRows, out totalRowCount);
}

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

As this is several time I am created serverside controls for .NET using excellent Bootstrap framework, I created a git here https://github.com/Gitzerai/Bootstrap.NET where I put controls that render in a bootstrap proper way.

Question 2

I found this to happen for me too. On a postback, the last page would "fill-out" the last page with rows from the first page, except the first row after the data. Example: if page size was 10 and I had 25 rows. The last page would show rows 21-25 initially, and then on a postback it would add rows 7-10.

I added the following "hack" to the gridview's RowCreated to prevent drawing these phantom rows. GV is the gridview. DataRowCount is a function which returns the number of rows from the datasource. PageIndex is a property uses a session to hold the current Page Index.

        If e.Row.RowType = DataControlRowType.DataRow Then
        Dim RowsLeft As Integer = DataRowCount() - (GV.PageSize * PageIndex)
        Dim RowsExpected As Integer

        If RowsLeft > GV.PageSize Then
            RowsExpected = GV.PageSize
        Else
            RowsExpected = RowsLeft
        End If

        If e.Row.RowIndex >= RowsExpected Then
            'Last page isn't full, need to force writing nothing out for extra rows
            e.Row.SetRenderMethodDelegate(New RenderMethod(AddressOf RenderNothing))
        End If
    End If

And then I added the following funtion:

Public Sub RenderNothing(writer As HtmlTextWriter, container As Control)
End Sub

Since RowCreated happens before ViewState is loaded, the GV's PageIndex wasn't available. So I created a property to hold the PageIndex. So my code now updates the new property and the property saves it to session and updates the GV's property. And this is the property I added

Private Const SS_PagerControl_PageIndex As String = "SSPagerControl_PageIndex"
<Bindable(True), CategoryAttribute("Paging"), DefaultValue("0")>
Public Property PageIndex As Integer
    Get
        If Session(SS_PagerControl_PageIndex) Is Nothing Then
            Return 0
        End If

        Return CInt(Session(SS_PagerControl_PageIndex))
    End Get
    Set(ByVal value As Integer)
        Session(SS_PagerControl_PageIndex) = value
        GV.PageIndex = value
        RebindGrid()
    End Set
End Property