Getting the items of a ComboBox with its DataSource filled

Question

Consider that there is a ComboBox which is populated through its DataSource property. Each item in the ComboBox is a custom object and the ComboBox is set with a DisplayMember and ValueMember.

IList<CustomItem> aItems = new List<CustomItem>();
//CustomItem has Id and Value and is filled through its constructor
aItems.Add(1, "foo"); 
aItems.Add(2, "bar");

myComboBox.DataSource = aItems;

Now the problem is that, I want to read the items as string that will be rendered in the UI. Consider that I don't know the type of each item in the ComboBox (CustomItem is unknown to me)

Is this possible ?

Answer 1

Binding:

ComboBox1.DataSource = aItems;
ComboBox1.DisplayMember = "Value";

Getting the item:

CustomItem ci = ComboBox1.SelectedValue as CustomItem;

edit: If all that you want to get is a list of all of the display values of the combobox

List<String> displayedValues = new List<String>();
foreach (CustomItem ci in comboBox1.Items)
    displayedValues.Add(ci.Value);

Answer 2

Create an Interface, say ICustomFormatter, and have those custom objects implement it.

interface ICustomFormatter
{
   public string ToString();
}

Then call the ToString() method.

EDIT: link to Decorator pattern.

Answer 3

Although slightly more computationally expensive, Reflection could do what you want:

using System.Reflection;    
private string GetPropertyFromObject(string propertyName, object obj)
    {
        PropertyInfo pi = obj.GetType().GetProperty(propertyName);
        if(pi != null)
        {
         object value = pi.GetValue(obj, null);
         if(value != null)
         {
          return value.ToString();
         }
        }
        //return empty string, null, or throw error
        return string.Empty;
    }