Strange behavior binding WPF combobox

Question

I'm having trouble binding to the text property of a combobox. It seems like it doesn't bind until I select something in the combobox. Then it works fine.

Here is the code straight from a test app:

View

<ComboBox ItemsSource="{Binding ListItems}"
          Text="{Binding Test}" />

ViewModel

class ViewModel : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;
    public ObservableCollection<string> ListItems { get; set; }
    public ViewModel()
    {
        ListItems = new ObservableCollection<string>();
        ListItems.Add("Southwest");
        ListItems.Add("South");
    }

    public string Test
    {
        get { return "South"; }
        set { PropertyChanged(this, new PropertyChangedEventArgs("Test")); }
    }
}

However, when I reverse the order of the observable collection items, everything works fine.

ListItems.Add("South");
ListItems.Add("Southwest");

What's going on here?

Answer 1

The text property doesn't work like this. Read this document: http://msdn.microsoft.com/en-us/library/system.windows.controls.combobox.text.aspx

Like suggested by hameleon86 use the selecteditem instead.

I think it Works if you reverse the order of your collection maybe because the Text property take the first item of the collection by default

Answer 2

I think you might want to do :

PropertyChanged(this, new PropertyChangedEventArgs("ListItems"));

After you inserted the element.