Windows Form DataGridView ComboBox Column: Change cell value on change

Hi ishuhasan21,

Please refer the sample below.

Code

private List<Country> countries;

private ComboBox cmbCountry;

public Form1()
{
    InitializeComponent();
}

private void Form1_Load(object sender, EventArgs e)
{
    countries = GetCountries();
    BindDataGridView();
}

private void dataGridView1_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
{
    if (dataGridView1.CurrentRow != null && dataGridView1.CurrentCell.ColumnIndex == 0)
    {
        cmbCountry = e.Control as ComboBox;
        if (cmbCountry != null)
        {
            cmbCountry.SelectedValueChanged += cmbCountry_SelectedValueChanged;
        }
    }
}

private void cmbCountry_SelectedValueChanged(object sender, EventArgs e)
{
    dataGridView1.CurrentRow.Cells[1].Value = dataGridView1.CurrentRow.Cells[0].EditedFormattedValue;
}

private void dataGridView1_CellLeave(object sender, DataGridViewCellEventArgs e)
{
    if (cmbCountry != null)
    {
        cmbCountry.SelectedValueChanged -= cmbCountry_SelectedValueChanged;
    }
}

private void dataGridView1_CellEndEdit(object sender, DataGridViewCellEventArgs e)
{
    if (e.ColumnIndex == 3 && dataGridView1.CurrentRow.Cells[3].Value != null && e.RowIndex == dataGridView1.RowCount - 1)
    {
        dataGridView1.Rows.Add();
    }
}

private List<Country> GetCountries()
{
    var countryList = new List<Country> {
                            new Country {Id=1, Name="USA"},
                            new Country {Id=2, Name="India"},
                            new Country {Id=3, Name="Canada"}
                        };
    return countryList;
}

private void BindDataGridView()
{
    dataGridView1.CellLeave += dataGridView1_CellLeave;
    dataGridView1.EditingControlShowing += dataGridView1_EditingControlShowing;
    dataGridView1.AllowUserToAddRows = false;

    DataGridViewComboBoxColumn country = new DataGridViewComboBoxColumn();
    country.Name = "Country";
    country.HeaderText = "Country";

    DataGridViewTextBoxColumn city = new DataGridViewTextBoxColumn();
    DataGridViewTextBoxColumn area = new DataGridViewTextBoxColumn();

    dataGridView1.Columns.Add(country);
    dataGridView1.Columns.Add("State", "State");
    dataGridView1.Columns.Add("City", "City");
    dataGridView1.Columns.Add("Area", "Area");

    ((DataGridViewComboBoxColumn)dataGridView1.Columns["Country"]).DisplayMember = "Name";
    ((DataGridViewComboBoxColumn)dataGridView1.Columns["Country"]).DataSource = countries;
    city.HeaderText = "City";
    area.HeaderText = "Area";

    dataGridView1.Rows.Add();
}

public class Country
{
    public int Id { get; set; }
    public string Name { get; set; }
}

Screenshot