Event that fires during DataGridViewComboBoxColumn SelectedIndexChanged

This answer is floating around in a couple of places.

Using the DataGridViewEditingControlShowingEventHandler will fire more events than you intend. In my testing it fired the event multiple times.

Also using the combo.SelectedIndexChanged -= event will not really remove the event, they just keep stacking.

Anyway, I found a solution that seems to work. I'm including a code sample below:

// Add the events to listen for
dataGridView1.CellValueChanged += new DataGridViewCellEventHandler(dataGridView1_CellValueChanged);
dataGridView1.CurrentCellDirtyStateChanged += new EventHandler(dataGridView1_CurrentCellDirtyStateChanged);



// This event handler manually raises the CellValueChanged event 
// by calling the CommitEdit method. 
void dataGridView1_CurrentCellDirtyStateChanged(object sender, EventArgs e)
{
    if (dataGridView1.IsCurrentCellDirty)
    {
        // This fires the cell value changed handler below
        dataGridView1.CommitEdit(DataGridViewDataErrorContexts.Commit);
    }
}

private void dataGridView1_CellValueChanged(object sender, DataGridViewCellEventArgs e)
{
    // My combobox column is the second one so I hard coded a 1, flavor to taste
    DataGridViewComboBoxCell cb = (DataGridViewComboBoxCell)dataGridView1.Rows[e.RowIndex].Cells[1];
    if (cb.Value != null)
    {
         // do stuff
         dataGridView1.Invalidate();
    }
}

That link is correct. Handle the EditingControlShowing event of DataGridView. In this event handler, check if the current column is of your interest. And, then create a temporary combobox object :-

ComboBox comboBox = e.Control as ComboBox;

MSDN has a sample: See in the example section here. Note the Inheritance Hierarchy & Class Syntax in the msdn link : -

public class DataGridViewComboBoxEditingControl : ComboBox, IDataGridViewEditingControl

private DataGridView dataGridView1 = new DataGridView();

private void AddColorColumn()
{
    DataGridViewComboBoxColumn comboBoxColumn =
        new DataGridViewComboBoxColumn();
    comboBoxColumn.Items.AddRange(
        Color.Red, Color.Yellow, Color.Green, Color.Blue);
    comboBoxColumn.ValueType = typeof(Color);
    dataGridView1.Columns.Add(comboBoxColumn);
    dataGridView1.EditingControlShowing +=
        new DataGridViewEditingControlShowingEventHandler(
        dataGridView1_EditingControlShowing);
}

private void dataGridView1_EditingControlShowing(object sender,
    DataGridViewEditingControlShowingEventArgs e)
{
    ComboBox combo = e.Control as ComboBox;
    if (combo != null)
    {
        // Remove an existing event-handler, if present, to avoid 
        // adding multiple handlers when the editing control is reused.
        combo.SelectedIndexChanged -=
            new EventHandler(ComboBox_SelectedIndexChanged);

        // Add the event handler. 
        combo.SelectedIndexChanged +=
            new EventHandler(ComboBox_SelectedIndexChanged);
    }
}

private void ComboBox_SelectedIndexChanged(object sender, EventArgs e)
{
    ((ComboBox)sender).BackColor = (Color)((ComboBox)sender).SelectedItem;
}

Give these two simple methods a go (the '1' in the top method is the index of the combobox column)

The line that you would make you modifications to would be the setter line cel.Value =, as you may change it to whatever you like.

---

    private void dataGridView1_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
    {
        if (dataGridView1.CurrentCell.ColumnIndex == 1 && e.Control is ComboBox)
        {
            ComboBox comboBox = e.Control as ComboBox;
            comboBox.SelectedIndexChanged -= LastColumnComboSelectionChanged;
            comboBox.SelectedIndexChanged += LastColumnComboSelectionChanged;
        }
    }

    private void LastColumnComboSelectionChanged(object sender, EventArgs e)
    {
        var currentcell = dataGridView1.CurrentCellAddress;
        var sendingCB = sender as DataGridViewComboBoxEditingControl;
        DataGridViewTextBoxCell cel = (DataGridViewTextBoxCell)dataGridView1.Rows[currentcell.Y].Cells[0];
        cel.Value = sendingCB.EditingControlFormattedValue.ToString();
    }

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