I have a Listbox bound to an object property which is of type List<MyCustomType>()
and I verified that the following code updates the listbox when the List is updated.
void On_MyObjProperty_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
{
MyListBox.Items.Refresh();
}
If you're still facing issues, scan the VS IDE output window (Ctrl+W, O) and see if you can spot any binding errors reported.
You set the DisplayMemberPath and the SelectedValuePath to "Name", so I assume that you have a class PhoneBookEntry with a public property Name.
Have you set the DataContext to your ConnectionViewModel object?
I copied you code and made some minor modifications, and it seems to work fine.
I can set the viewmodels PhoneBookEnty property and the selected item in the combobox changes, and I can change the selected item in the combobox and the view models PhoneBookEntry property is set correctly.
Here is my XAML content:
<Window x:Class="WpfApplication6.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1" Height="300" Width="300">
<Grid>
<StackPanel>
<Button Click="Button_Click">asdf</Button>
<ComboBox ItemsSource="{Binding Path=PhonebookEntries}"
DisplayMemberPath="Name"
SelectedValuePath="Name"
SelectedValue="{Binding Path=PhonebookEntry}" />
</StackPanel>
</Grid>
</Window>
And here is my code-behind:
namespace WpfApplication6
{
/// <summary>
/// Interaction logic for Window1.xaml
/// </summary>
public partial class Window1 : Window
{
public Window1()
{
InitializeComponent();
ConnectionViewModel vm = new ConnectionViewModel();
DataContext = vm;
}
private void Button_Click(object sender, RoutedEventArgs e)
{
((ConnectionViewModel)DataContext).PhonebookEntry = "test";
}
}
public class PhoneBookEntry
{
public string Name { get; set; }
public PhoneBookEntry(string name)
{
Name = name;
}
public override string ToString()
{
return Name;
}
}
public class ConnectionViewModel : INotifyPropertyChanged
{
public ConnectionViewModel()
{
IList<PhoneBookEntry> list = new List<PhoneBookEntry>();
list.Add(new PhoneBookEntry("test"));
list.Add(new PhoneBookEntry("test2"));
_phonebookEntries = new CollectionView(list);
}
private readonly CollectionView _phonebookEntries;
private string _phonebookEntry;
public CollectionView PhonebookEntries
{
get { return _phonebookEntries; }
}
public string PhonebookEntry
{
get { return _phonebookEntry; }
set
{
if (_phonebookEntry == value) return;
_phonebookEntry = value;
OnPropertyChanged("PhonebookEntry");
}
}
private void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
public event PropertyChangedEventHandler PropertyChanged;
}
}
Edit: Geoffs second example does not seem to work, which seems a bit odd to me. If I change the PhonebookEntries property on the ConnectionViewModel to be of type ReadOnlyCollection, the TwoWay binding of the SelectedValue property on the combobox works fine.
Maybe there is an issue with the CollectionView? I noticed a warning in the output console:
System.Windows.Data Warning: 50 : Using CollectionView directly is not fully supported. The basic features work, although with some inefficiencies, but advanced features may encounter known bugs. Consider using a derived class to avoid these problems.
Edit2 (.NET 4.5): The content of the DropDownList can be based on ToString() and not of DisplayMemberPath, while DisplayMemberPath specifies the member for the selected and displayed item only.
Best Answer
You cannot do it this way.
To achieve that kind of trick, you would need your items to be "holder classes" that expose a property you can bind your textbox to.
To understand it, imagine the following pseudo sequence of calls:
Your template (the DataTemplate with the listbox) is loaded and the item (which I assume is a string in your case) gets passed in. At this point, it only knows the string, and cannot influence anything upwards. A two-way binding cannot influence the collection because the template does not know in which context it is being used, so it cannot reach back to the original collection and modify its contents. For that matter, this is the same thing for the TextBox. If it is not given a conainer and a property name, it has nowhere to "store back" the changes. This basically the same as passing a string into a function call. The function cannot change which string was passed in (ignoring tricks such as by-reference argument passing).
To get back to your case, you need to build a collection of objects which expose a property containing the value that needs to be edited:
Then you can bind your ListBox to a collection of those items and modifiy your datatemplate: