Event Handling in Windows Forms MultiColumn ComboBox

2 Oct 20232 minutes to read

The events of ComboBoxAdv present in the MultiColumnComboBox.

Selection events

The MultiColumnComboBox fires different events for the different user interaction scenarios. The occurrence and order of the events are tabulated below:

Scenarios	Selection Changed Committed	Selected Value Changed	Selected Index Changed	Validating/Validated
TextArea-Change Selection by Keys	Yes:1	Yes:2	Yes:3	No
TextArea-On AutoComplete	No	No	No	No
Drop-Down List-Change Selection by Keys	No	Yes:1	Yes:2	No
Drop-Down List-Change Selection by Mouse Move	No	No	No	No
Drop-Down Close by Enter Key	Yes:1	No	No	No
Drop-Down Close by Escape Key	No	No	No	No
Drop-Down Close by clicking	Yes:1	Yes:2	Yes:3	No
Losing Focus	Yes:2 (in DropDownStyle.DropDown (editable) mode only)	No	No	Yes:1
Changing Text Property in Code	Yes:1	No	No	No

You can refer the following topics which gives you an idea on implementing the above events.

• How to display multiple members in a MultiColumnComboBox?
• How to retrieve the columns other than Display and Value members in a MultiColumnComboBox?

SelectedValueChanged event

This event is handled when the selected value is changed in the combobox. This section discusses a use case illustrating the event.

Setting text according to selection

The process of accessing the selected item is a complex one. We need to access DataRowView from the control and then to get the values. Include the below code in the SelectedValueChanged event handler to set the text of MultiColumnComboBox to the text in the first column of the selected row.

C#

private void multiColumnComboBox1_SelectedValueChanged(object sender, System.EventArgs e) 
{
    ComboBoxBaseDataBound c=multiColumnComboBox1 as ComboBoxBaseDataBound;
    if (c.SelectedIndex!=-1)        
    {
        // Sets the text of MultiColumnComboBox to the text in the first column of selected row.
        DataRowView drv=c.Items[c.SelectedIndex] as DataRowView;
        c.Text=drv.Row[1].ToString();
    }
}

VB.NET

Private Sub multiColumnComboBox1_SelectedValueChanged(ByVal sender As Object, ByVal e As System.EventArgs) 
Dim c As ComboBoxBaseDataBound = CType(multiColumnComboBox1, ComboBoxBaseDataBound) 
If Not (c.SelectedIndex = -1) Then 

' Sets the text of MultiColumnComboBox to the text in the first column of selected row.
Dim drv As DataRowView = CType(c.Items(c.SelectedIndex), DataRowView) 
c.Text = drv.Row(1).ToString 
End If 
End Sub

SelectedIndexChanged event

This event is illustrated in How to retrieve the columns other than Display and Value members in a MultiColumnComboBox? topic.