To reproduce:

1. Run code
2. Enter Walter from keyboard
3. Click button.

Observed:

J

Expected:

W


How to fix ?

Andrus

using System.Windows.Forms;
using System.Collections.Generic;

class testForm : Form {

Storage s = new Storage();

testForm() {
Customer c = new Customer();
c.Id = "J";
c.Name = "John";

List<Customer> l = new List<Customer>();
l.Add(c);
c = new Customer();
c.Id = "W";
c.Name = "Walter";
l.Add(c);

ComboBox cm = new ComboBox();
cm.DisplayMember = "Name";
cm.ValueMember = "Id";
cm.DataSource = l;

s.CustId = "W";

cm.DataBindings.Add("SelectedValue", s, "CustId");

Controls.Add(cm);
Button b = new Button();
b.Top = 80;
b.Click += new System.EventHandler(b_Click);
Controls.Add(b);

}

void b_Click(object sender, System.EventArgs e) {
if (s.CustId == null)
MessageBox.Show("Empty combobox must store null value");
else
MessageBox.Show(s.CustId.ToString());

}

class Customer {
public string Id { get; set; }
public string Name { get; set; }

}

class Storage {
public string CustId { get; set; }
}

static void Main() {
Application.Run(new testForm());
}
}