Generating row numbers automatically in the header of dataGridView

I'm new to using the C#/.NET programming Language and I have created a DataGridView for adding, editing and deleting records.

I am using Visual Studio 2010 for coding. I have put in an unbound column for row number and have this method for displaying the auto generated row numbers.

private void dataGridView1_DefaultValuesNeeded(object sender, DataGridViewRowEventArgs e)
        {
            foreach (DataGridViewRow row in dataGridView1.Rows)
            {
                row.Cells["rownumber"].Value = row.Index + 1;                
            }
            e.Row.Cells["min_bracket"].Value = 0;
            e.Row.Cells["max_bracket"].Value = 0;
            e.Row.Cells["tax_percent"].Value = 0;
            e.Row.Cells["add_amount"].Value = 0;
        }

This does work when inserting values into the datagrid but does not show any numbers in the rownumber column when retrieving values.

How do 开发者_JAVA百科I get to have auto generated numbers in the header instead of having to create an unbound column like I have that works when inserting rows and retrieving records?

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To display text in the row header you can use the Row.HeaderCell.Value as shown below:

void dataGridView1_DataBindingComplete(object sender, DataGridViewBindingCompleteEventArgs e)
{
    DataGridView gridView = sender as DataGridView;
    if (null != gridView)
    {
        foreach (DataGridViewRow r in gridView.Rows)
        {
            gridView.Rows[r.Index].HeaderCell.Value = (r.Index + 1).ToString();
        }
    }
}

This only displays the row number of the new row when the user begins typing in it. Not sure if there is a simple way of always showing the row number on the new row.

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I use a ViewState to do this, as follows:

1. Add a template column for the row count
2. Bind its content to a property like SeqNo
3. Create the property SeqNo in your code-behind, returning the current row count (try the below code)

int _seq = 0;

public int SeqNo {
  get {
    if (ViewState["seq"] == null) {
        ViewState["seq"] = 1;
    } else {
        ViewState["seq"] = int.Parse(ViewState["seq"].ToString()) + 1; 
    }
    _seq = int.Parse(ViewState["seq"].ToString());
    return _seq;
  }
} 

And for the aspx side ,add the template Column to your interest GridView as the following

                 <asp:TemplateField HeaderText="" >
                    <ItemTemplate>
                        <%=SeqNo%>
                    </ItemTemplate>
                </asp:TemplateField>

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I thought this was a very simple solution for Windows Forms. You can customise the drawing as you wish.

Create the following class:

Public Class DataGridViewNumberedRow
    Inherits DataGridViewRow

    Protected Overrides Sub PaintHeader(graphics As System.Drawing.Graphics, clipBounds As System.Drawing.Rectangle, rowBounds As System.Drawing.Rectangle, rowIndex As Integer, rowState As System.Windows.Forms.DataGridViewElementStates, isFirstDisplayedRow As Boolean, isLastVisibleRow As Boolean, paintParts As System.Windows.Forms.DataGridViewPaintParts)
        MyBase.PaintHeader(graphics, clipBounds, rowBounds, rowIndex, rowState, isFirstDisplayedRow, isLastVisibleRow, paintParts)

        graphics.DrawString(rowIndex + 1, SystemFonts.MenuFont, Brushes.Black, rowBounds)
    End Sub
End Class

Then, set the default row template for your data grid view like this:

DataGridView1.RowTemplate = New DataGridViewNumberedRow