Question

I have an object with two arrays of strings. The object is data bound to a listbox. One list is bound as the list’s ItemsSource. The other, which is the thing causing me trouble, needs to be bound to a combobox that’s part of a DataTemplate that is set to the list’s ItemTemplate. Basically each item on the listbox has the corresponding element of the first list and a combo box that contains the second list. In other words, every item in the list has the same combobox of choices.

The problem comes from the fact that it winds up that the DataTemplate is data bound the first list. I was expecting the DataTemplate to be databound to the object that contains both lists. Now, with that happening, I can’t figure out what kind of binding syntax I need to get at the “parent” of the DataContext, if that’s even possible.

Can someone point me in the right direction?

Thanks!

Answer 1

If I’m understanding you correctly, you can set the DataContext of your ListBox to an instance of a class (in my example I do it in code by: list.DataContext = myclass;) and you want to set the ItemSource of your listbox to a list in the class (ie Items) and the itemssource of your combobox to another list in the class (ie Values). Here’s my xaml that seems to work:

<ListBox Name="list" ItemsSource="{Binding Items}">
    <ListBox.ItemTemplate>
        <DataTemplate>
            <StackPanel>
                <TextBlock Text="{Binding}"/>
                <ComboBox ItemsSource=
                          "{Binding RelativeSource={RelativeSource FindAncestor, 
                                                    AncestorType={x:Type ListBox}}, 
                                    Path=DataContext.Values}"
                />
            </StackPanel>
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>

and heres the class that I’m binding to:

public class AClass
{

    protected List<string> _Items;
    public List<string> Items
    {
        get
        {
            if (_Items == null)
            {
                _Items = new List<string>();
            }
            return _Items;
        }
    }


    protected List<string> _Values;
    public List<string> Values
    {
        get
        {
            if (_Values == null)
            {
                _Values = new List<string>();
            }
            return _Values;
        }
    }
}

In code I created an instance of AClass, added Items and Values, and set the instance to the DataContext of the listbox.