Question

I have this DependencyProperty which holds an entity with a property that is a collection (ShoutBox.Entities):

public static readonly DependencyProperty ShoutBoxProperty = DependencyProperty.Register("ShoutBox",typeof (ShoutBox),typeof (ShoutBoxViewerControl));

public ShoutBox ShoutBox
{
    get { return (ShoutBox) GetValue(ShoutBoxProperty); }
    set { SetValue(ShoutBoxProperty, value); }
}

It is being binded in xaml like such:

<ItemsControl ItemsSource="{Binding ShoutBox.Entries}">
.
.
</ItemsControl>

When I bind it the first time, it works as expected but there are times when I need to add items to the collection (with a method that is in the same control), like such:

public void AddNewEntry(ShoutBoxEntry newEntry)
{
    Dispatcher.Invoke(new Action(() =>{
        ShoutBox.Entries.Add(newEntry); //Adding directly the the Dependency property
    }));
}

The problem is that when I add a new element with the above method, the item isn’t being displayed in the ItemsControl.

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My question is, why isn’t the new element that I am adding isn’t being displayed in the ItemsControl ?

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[Edit]

Entries (ShoutBox.Entries) is of type List<ShoutBoxEntry>

Answer 1

What is the type of Entries? It either needs to be ObservableCollection or implement ICollectionChanged. Otherwise the binding doesn’t know that a new item has been added.