Add Gridview Row AFTER Header

问题:

i'm trying to add a new headerrow to a Gridview. This row should appear below the original headerrow.

As far as I know I have two events to choose from:

1.) Gridview_RowDataBound 2.) Gridview_RowCreated

Option 1 is not an option as the grid is not binding the data on each postback. Option 2 does not work as expected. I can add the row, but it is added before the HeaderRow because the HeaderRow itself is not added yet in this event...

Please assist, thank you!

Code: (InnerTable property is exposed by custom gridview)

    Private Sub GridView1_RowDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles GridView1.RowDataBound
    If e.Row.RowType = DataControlRowType.Header Then
        Dim r As New GridViewRow(-1, -1, DataControlRowType.Header, DataControlRowState.Normal)

        For Each c As DataControlField In CType(sender, GridView).Columns
            Dim nc As New TableCell
            nc.Text = c.AccessibleHeaderText
            nc.BackColor = Drawing.Color.Cornsilk
            r.Cells.Add(nc)
        Next

        Dim t As Table = GridView1.InnerTable
        t.Controls.Add(r)
    End If
End Sub

回答1:

Since this is a custom GridView, why don't you consider overriding the CreateChildControls method?

I.e (sorry, C#):

protected override void CreateChildControls()
{
    base.CreateChildControls();

    if (HeaderRow != null)
    {
        GridViewRow header = CreateRow(-1, -1, DataControlRowType.Header, DataControlRowState.Normal);
        for (int i = 0; i < Columns.Count; i++)
        {
            TableCell cell = new TableCell();
            cell.Text = Columns[i].AccessibleHeaderText;
            cell.ForeColor = System.Drawing.Color.Black;
            cell.BackColor = System.Drawing.Color.Cornsilk;
            header.Cells.Add(cell);
        }

        Table table = (Table)Controls[0];
        table.Rows.AddAt(1, header);
    }
}

UPDATE As was mentioned by Ropstah, the sniplet above does not work with pagination on. I moved the code to a PrepareControlHierarchy and now it works gracefully with pagination, selection, and sorting.

protected override void PrepareControlHierarchy()
{
    if (ShowHeader && HeaderRow != null)
    {
        GridViewRow header = CreateRow(-1, -1, DataControlRowType.Header, DataControlRowState.Normal);
        for (int i = 0; i < Columns.Count; i++)
        {
            TableCell cell = new TableCell();
            cell.Text = Columns[i].AccessibleHeaderText;
            cell.ForeColor = System.Drawing.Color.Black;
            cell.BackColor = System.Drawing.Color.Cornsilk;
            header.Cells.Add(cell);
        }

        Table table = (Table)Controls[0];
        table.Rows.AddAt(1, header);
    }

    //it seems that this call works at the beginning just as well
    //but I prefer it here, since base does some style manipulation on existing columns
    base.PrepareControlHierarchy();
}

回答2:

Nice work guys, I used your technique for grouping my AJAX enabled gridview, and I searched for a long, long time. Cheers.

protected override void PrepareControlHierarchy()
{
    if (GroupColumns)
    {
        #region Group Column

        Table table = (Table)Controls[0];

        string lastValue = string.Empty;
        foreach (GridViewRow gvr in this.Rows)
        {
            string currentValue = gvr.Cells[GroupColumnIndex].Text;

            if (lastValue.CompareTo(currentValue) != 0)
            {
                // there's been a change in value in the sorted column
                int rowIndex = table.Rows.GetRowIndex(gvr);

                // Add a new sort header row
                GridViewRow sortRow = new GridViewRow(rowIndex, rowIndex, DataControlRowType.DataRow, DataControlRowState.Normal);

                TableCell sortCell = new TableCell();
                TableCell blankCell = new TableCell();

                sortCell.ColumnSpan = this.Columns.Count - 1;
                sortCell.Text = string.Format("{0}", currentValue);

                blankCell.CssClass = "group_header_row";
                sortCell.CssClass = "group_header_row";

                // Add sortCell to sortRow, and sortRow to gridTable
                sortRow.Cells.Add(blankCell);
                sortRow.Cells.Add(sortCell);
                table.Controls.AddAt(rowIndex, sortRow);

                // Update lastValue
                lastValue = currentValue;
            }
        }

        #endregion
    }

    HideColumns();

    base.PrepareControlHierarchy();
} 

回答3:

Try this when you add the row to the InnerTable:

t.Controls.AddAt(1, r)

Here's a quick basic test I did, which seems to work OK:

Protected Sub gridview_DataBound(ByVal sender As Object, ByVal e As System.EventArgs) Handles gridview.DataBound
    Dim g As GridView = CType(sender, GridView)

    Dim r As New GridViewRow(0, -1, DataControlRowType.Header, DataControlRowState.Normal)
    Dim th As New TableHeaderCell()
    th.ColumnSpan = g.Columns.Count
    th.Text = "This is my new header"
    r.Cells.Add(th)

    Dim t As Table = CType(g.Controls(0), Table)
    t.Rows.AddAt(1, r)
End Sub