What event catches a change of value in a combobox in a DataGridViewCell?

Question

I want to handle the event when a value is changed in a ComboBox in a DataGridView cell.

There's the CellValueChanged event, but that one doesn't fire until I click somewhere else inside the DataGridView.

A simple ComboBox SelectedValueChanged does fire immediately after a new value is selected.

How can I add a listener to the combobox that's inside the cell?

Answer 1

The above answer led me down the primrose path for awhile. It does not work as it causes multiple events to fire and just keeps adding events. The problem is that the above catches the DataGridViewEditingControlShowingEvent and it does not catch the value changed. So it will fire every time you focus then leave the combobox whether it has changed or not.

The last answer about "CurrentCellDirtyStateChanged" is the right way to go. I hope this helps someone avoid going down a rabbit hole.

Here is some code.

        // 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 (this.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();
        }
     }

Answer 2

This is the code, which will fire the event of the selection in the comboBox in the dataGridView:

public Form1()
    {
        InitializeComponent();

        DataGridViewComboBoxColumn cmbcolumn = new DataGridViewComboBoxColumn();
        cmbcolumn.Name = "cmbColumn";
        cmbcolumn.HeaderText = "combobox column";
        cmbcolumn.Items.AddRange(new string[] { "aa", "ac", "aacc" });
        dataGridView1.Columns.Add(cmbcolumn);
        dataGridView1.EditingControlShowing += new DataGridViewEditingControlShowingEventHandler(dataGridView1_EditingControlShowing);
    }

    private void dataGridView1_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
    {
        ComboBox combo = e.Control as ComboBox;
        if (combo != null)
        {
            combo.SelectedIndexChanged -= new EventHandler(ComboBox_SelectedIndexChanged);
            combo.SelectedIndexChanged += new EventHandler(ComboBox_SelectedIndexChanged);
        }
    }

    private void ComboBox_SelectedIndexChanged(object sender, EventArgs e)
    {
        ComboBox cb = (ComboBox)sender;
        string item = cb.Text;
        if (item != null)
            MessageBox.Show(item);
    }

Answer 3

You can also handle the CurrentCellDirtyStateChanged event which gets called whenever a value is changed, even if it's not commited. To get the selected value in the list, you would do something like:

var newValue = dataGridView.CurrentCell.EditedFormattedValue;

Answer 4

ComboBox cmbBox = (ComboBox)sender;                
MessageBox.Show(cmbBox.SelectedValue.ToString());