DataBinding between two custom listbox

Question

What I want

I have two custom ListBox inside my UserControl.

My custom ListBox1 has a private List<Element> SubList which is a sub-list of its elements. This custom control implements the PropertyChanged of INotifyPropertyChanged etc etc.

My ListBox2 has to display this sub-list.

Both of them are also using DataTemplate but I do not think it will be the problem here so I will not take care of this part here. If I am wrong, let me know and I will update my example.

What I tried

<UserControl>
        <local:ListBox1 x:Name="ListBox1" 
                         DataContext="{Binding MyFullList}"/>
        <local:ListBox2 x:Name="ListBox2" 
                        DataContext="{Binding ElementName=ListBox1}"
                        Content="{Binding Path=SubList}"/>
</UserControl>

It's giving me inside my ListBox2:

(Collection)

I tried using just one element instead of the list of elements and it was working. I also tried like this:

<UserControl>
            <local:ListBox1 x:Name="ListBox1" 
                             DataContext="{Binding MyFullList}"/>
            <local:ListBox2 x:Name="ListBox2" 
                            DataContext="{Binding ElementName=ListBox1, Path=SubList}"/>
</UserControl>

But it is giving me nothing... I also tried using ObservableCollection instead of List but still nothing.

My Questions

What should be my Binding to fill ListBox2 with the SubList of ListBox1? What am I doing wrong ?

Answer 1

I found the solution to my problem. I tried using a list already filled and it was working. So the problem was during the update of the ListBox2 and not the DataBinding.

I do not know why but the List named SubList was not updating the ListBox2 even if it was triggering the OnPropertyChanged event, etc.

I just needed to change my SubList to an ObservableCollection and the following code is doing the DataBinding correctly :

<UserControl>
            <local:ListBox1 x:Name="ListBox1" 
                             DataContext="{Binding MyFullList}"/>
            <local:ListBox2 x:Name="ListBox2" 
                            DataContext="{Binding ElementName=ListBox1, Path=SubList}"/>
</UserControl>