Multi Column ComboBox

• Download source files - 14 Kb
• Download demo project - 38.6 Kb

Introduction

This is a simple example of how to display table values (i.e. multiple columns) in a combo box. For the dropdown window, a form with a ListView docked to fill can be used. The MultiColumnCombobox class is inherited from the System.Windows.Forms.Combobox class.

protected override void OnDropDown(System.EventArgs e){
    Form parent = this.FindForm();
    if(this.dataTable != null || this.dataRows!= null){
        MultiColumnComboPopup popup = new 
                            MultiColumnComboPopup(this.dataTable,
                            ref this.selectedRow,columnsToDisplay);
        popup.AfterRowSelectEvent+=
                            new AfterRowSelectEventHandler
                            (MultiColumnComboBox_AfterSelectEvent);
        popup.Location = new Point(parent.Left + 
                            this.Left + 4 ,parent.Top + 
                            this.Bottom + this.Height);
        popup.Show();
        ..........................

The OnDropDown event of the ComboBox is overridden to display our popup from. The popup form should never be a modal, because the popup has to close, if the user decides to click elsewhere other than the grid on the dropdown form. To check where the user has selected something, I use the popup.AfterRowSelectEvent, to fire an event on the MulticolumnComboBox. To use the MulticolumnComboBox do the following:

multiColumnComboBox1.Table = dtable;//DataTable
//Column to display after selection
multiColumnComboBox1.DisplayMember = "Band";
multiColumnComboBox1.ColumnsToDisplay = new 
    string[]{"Band","Song","Album"};//columns to display
//in the dropdown grid

After the DataTable is assigned to the combo, the dropdown looks like this:

After Selection, the DisplayMember of that row is displayed.

The SourceCode is pretty much self-explanatory, download it and try it out.