Created Combobox Column of datagridview is not visible inside DataBindingComplete

Question

I am developing a Windows Form application in C#. I have a DataGridView which displays data from a table. I populate the grid using a Data table and I have a Combobox Column added to the DataGridView . I need to preset the Combox value based on the value of another column of the grid. However inside the DataBindingComplete event of the DataGridView where I want to set the Idex of the Combobox I cant see the newly added combobox column. Following code would better explain the thing.

Code to load the DataGridView.

        DataTable family = new DataTable();
        family.Columns.Add("tin", typeof(string));
        family.Columns.Add("ftin", typeof(string));
        family.Columns.Add("fullname", typeof(string));
        family.Columns.Add("age", typeof(string));
        family.Columns.Add("gender", typeof(string));
        family.Columns.Add("fathername", typeof(string));
        family.Columns.Add("mothername", typeof(string));

        family.Columns.Add("relationshipid", typeof(string));
        family.Columns.Add("address", typeof(string));

        family.Columns.Add("cat", typeof(string));

//read data

  cmd.CommandText = "SELECT        fullname,fathername,mothername,relationshipid,tin,ftin,address,age,gender FROM nprmembers where ftin='" + s.Trim() + "' Order By tin  ";
   var reader = cmd.ExecuteReader();

//

      while (reader.Read())
            {
                  string gndr = GetGender(reader.GetString(8).Trim());
                 family.Rows.Add(reader.GetString(4).TrimStart(),   
    reader.GetString(5).TrimStart(), reader.GetString(0).TrimStart(),  
    reader.GetString(7).TrimStart(), gndr, reader.GetString(1).TrimStart(), 
    reader.GetString(2).TrimStart(), reader.GetString(3).TrimStart(), 
  reader.GetString(6).TrimStart(),"2");


            }
            reader.Close();
            reader.Dispose();

//Set Data Source

        dtGrdViewFamily.DataSource = family;
        dtGrdViewFamily.AutoGenerateColumns = false;
        dtGrdViewFamily.Columns[0].HeaderText = "TIN";
        dtGrdViewFamily.Columns[0].Width = 180;
        dtGrdViewFamily.Columns[1].Visible = false;

        dtGrdViewFamily.Columns[2].HeaderText = "Name";
        dtGrdViewFamily.Columns[2].Width = 180;
        dtGrdViewFamily.Columns[3].HeaderText = "DOB";
        dtGrdViewFamily.Columns[3].Width = 70;
        dtGrdViewFamily.Columns[4].HeaderText = "Gender";
        dtGrdViewFamily.Columns[4].Width = 60;
        dtGrdViewFamily.Columns[5].HeaderText = "Father";
        dtGrdViewFamily.Columns[6].HeaderText = "Mother";
        dtGrdViewFamily.Columns[7].HeaderText = "Relation";
        dtGrdViewFamily.Columns[8].HeaderText = "Address";

        dtGrdViewFamily.Columns[9].HeaderText = "cat";
        dtGrdViewFamily.Columns[9].Width = 2;
        dtGrdViewFamily.Columns[9].Visible = false;

Here I add new Column

//I have added this to stop repeat of this column every time a new set of data is loaded to the grid

 if (dtGrdViewFamily.ColumnCount == 10)
  {
            //Category
            DataGridViewComboBoxColumn rcCategories = new DataGridViewComboBoxColumn();
            rcCategories.HeaderText = "Category";
            rcCategories.DataSource = GetRCCategories();
            rcCategories.DisplayMember = "Values";
            rcCategories.ValueMember = "Keys";
            dtGrdViewFamily.Columns.Add(rcCategories);


        }

At this point the grid is visible with a Combobox with a set of values. Now I want to set Combobox valuees of each rows of the grid with the content of another column of the grid. So I call dtGrdViewFamily_DataBindingComplete event. The code is

 private void dtGrdViewFamily_DataBindingComplete(object sender, DataGridViewBindingCompleteEventArgs e)
    {
        foreach(DataGridViewRow row in dtGrdViewFamily.Rows)

        {
            if(!row.IsNewRow)
            {
                row.Cells["Category"].Value = row.Cells["cat"].Value;
                //AT THIS POINT it FAILS TO IDENTIFY THE CATEGORY FIELD
            }
        }

    } 

The debugger shows only 10 fields (0-9) of the dtGrdViewFamily. The Category combobox field is missing. Why so? and how I achieve the objective of preselecting value of the combobox. Thanks

Answer 1

Got a solution. The problem seems, DataBindingComplete is called before Combox of the grid are loaded. So I shifted the code for adding combox to the grid to DataBindingComplete event an used a DataGridViewComboBoxCell instead of DataGridViewComboBoxColumn. The changed code for DatabindingComplete is -

private void dtGrdViewFamily_DataBindingComplete(object sender, DataGridViewBindingCompleteEventArgs e)
    {
         //if(!(dtGrdViewFamily.Columns.Contains("Category"))
         //    return;
        foreach(DataGridViewRow row in dtGrdViewFamily.Rows)

        {
            if (!row.IsNewRow)
            {
            DataGridViewComboBoxCell rcCategories = new DataGridViewComboBoxCell();
            rcCategories.DataSource = GetRCCategories();
            rcCategories.DisplayMember = "Values";
            rcCategories.ValueMember = "Keys";

            row.Cells[9] = rcCategories;

        }
        }

    }

It works fine now.