editable column in Gridview

Hi

  It is giving error 'DataControlField does nor contain a definition for ReadOnly

grdPlanning.DataSource = BookPlanningResult;
                    foreach (DataControlField column in grdPlanning.Columns)
                    {
                        column.ReadOnly = true;
                    }

Thanks

foreach (DataControlField column in grdPlanning.Columns)
{
    column.ReadOnly = true;
}
grdPlanning.Columns[grdPlanning.Columns.Count - 1].ReadOnly = false; // set the last column (Date) to be editable

protected void grdPlanning_RowEditing(object sender, GridViewEditEventArgs e)
{
    // Get the cell that contains the Date column for the selected row
    TableCell dateCell = grdPlanning.Rows[e.NewEditIndex].Cells[grdPlanning.Columns.Count - 1];

    // Make the cell editable
    dateCell.ReadOnly = false;

    // Set the input type of the cell to "text" to allow the user to enter a date
    dateCell.Attributes.Add("type", "text");

    // Set the format of the date input to "dd-mm-yyyy" using HTML5 "pattern" attribute
    dateCell.Attributes.Add("pattern", "\\d{2}-\\d{2}-\\d{4}");

    // Set the placeholder text to show the expected date format
    dateCell.Attributes.Add("placeholder", "dd-mm-yyyy");
}

protected void grdPlanning_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
    // Get the new value entered by the user for the Date column
    string newDate = e.NewValues[e.NewValues.Count - 1].ToString();

    // Validate the date format using regular expressions
    Regex dateFormat = new Regex(@"^\d{2}-\d{2}-\d{4}$");
    if (!dateFormat.IsMatch(newDate))
    {
        // Cancel the update and show an error message
        e.Cancel = true;
        ScriptManager.RegisterStartupScript(this, GetType(), "InvalidDate", "alert('Please enter the date in dd-mm-yyyy format.');", true);
    }
}