change values in Datagridview when it has been binded

Question

In my project, I am trying to change values in a column of DataGridView after binding it with DataSet. Something like this:

dgvMain --> DataGridView
dsMainPatients --> DataSet
dsMainDoctors -->  DataSet

---

  dgvMain.DataSource = null;
  dgvMain.DataSource = dsMainPatients.Tables[0];

---

foreach (DataGridViewRow r in dgvMain.Rows)
{
    DataGridViewTextBoxCell txt = new DataGridViewTextBoxCell();
    for (int intCount = 0; intCount < dsMainDoctors.Tables[0].Rows.Count; intCount++)
    {
        if (r.Cells[4].Value.ToString().Equals(dsMainDoctors.Tables[0].Rows[intCount][0].ToString()))
        {
             txt.Value = dsMainDoctors.Tables[0].Rows[intCount][1].ToString();
             r.Cells[4] = txt;   //dgvMain[4, r.Index] = txt; (also tried)
        }
    }                            
 }

My solution is entering in to the if statement successfully and even txt holds correct value but I dont know what is happening at r.Cells[4] that it has the same old previous value.
Everything is correct eventhough the value in the grid columns are not changing.. How to change them?

Answer 1

You need to use CellFormatting event of DataGridView :

private void dataGridView1_CellFormatting(object sender, DataGridViewCellFormattingEventArgs e)
{
    if (e.ColumnIndex == 4)
    {
         for (int intCount = 0; intCount < dsMainDoctors.Tables[0].Rows.Count; intCount++)
         {
             if (e.Value.ToString().Equals(dsMainDoctors.Tables[0].Rows[intCount][0].ToString()))
             {
                  e.Value = txt.Value = dsMainDoctors.Tables[0].Rows[intCount][1].ToString();
             }
         }
     }
}