Winforms ComboBox Modify Display Text

Question

Hello All

I am working on a winforms application, and am trying to find a way to modify the displayed text when the collection is bound to the control.

           foreach (var time in timeTable)
            {
                comboBox.Items.Add(time);
            }

            comboBox.DataSource = timeTable;
            comboBox.DisplayMember = nameof(TimeTable.DisplayText);
            comboBox.ValueMember = nameof(TimeTable.TimeSpan);

As of now the combobox looks like this: (2hr)

I want to look like this "TimeFrame: (2hr)"

How would I modify this? I was looking at using ownerdraw, but I am not sure how to go about that route.

I cannot modify the class that this is dependant on as the properties are readonly. I have no control over this.

Answer 1

You need to create your own class as shown below (Id is optional), keep in mind this is a proof of concept.

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        comboBox1.DataSource = new List<TimeItem>
        {
            new () { Id = 1, Time = new TimeSpan(12, 0, 0) },
            new () { Id = 2, Time = new TimeSpan(10, 0, 0) },
            new () { Id = 3, Time = new TimeSpan(8,0,0)}
        };
    }

    private void GetButton_Click(object sender, EventArgs e)
    {
        var current = comboBox1.SelectedItem as TimeItem;
        MessageBox.Show(current!.Id.ToString());
    }
}

public class TimeItem
{
    public int Id { get; set; }
    public TimeSpan Time { get; set; }
    public override string ToString() => $"TimeFrame ({Time:hh})";

}