binding a command inside a listbox item to a property on the viewmodel parent

Question

I've been working on this for about an hour and looked at all related SO questions.

My problem is very simple:

I have HomePageVieModel:

HomePageVieModel
+IList<NewsItem> AllNewsItems
+ICommand OpenNews

My markup:

<Window DataContext="{Binding HomePageViewModel../>
<ListBox ItemsSource="{Binding Path=AllNewsItems}">
 <ListBox.ItemTemplate>
   <DataTemplate>
       <StackPanel>
        <TextBlock>
           <Hyperlink Command="{Binding Path=OpenNews}">
               <TextBlock Text="{Binding Path=NewsContent}" />
           </Hyperlink>
        </TextBlock>
      </StackPanel>
    </DataTemplate>
</ListBox.ItemTemplate>

The list shows fine with all the items, but for the life of me whatever I try for the Command won't work:

<Hyperlink Command="{Binding Path=OpenNewsItem, RelativeSource={RelativeSource AncestorType=vm:HomePageViewModel, AncestorLevel=1}}">
<Hyperlink Command="{Binding Path=OpenNewsItem, RelativeSource={RelativeSource AncestorType=vm:HomePageViewModel,**Mode=FindAncestor}**}">
<Hyperlink Command="{Binding Path=OpenNewsItem, RelativeSource={RelativeSource AncestorType=vm:HomePageViewModel,**Mode=TemplatedParent}**}">

I just always get :

System.Windows.Data Error: 4 : Cannot find source for binding with reference .....

Update I am setting my ViewModel like this? Didn't think this would matter:

 <Window.DataContext>
        <Binding Path="HomePage" Source="{StaticResource Locator}"/>
    </Window.DataContext>

I use the ViewModelLocator class from the MVVMLight toolkit which does the magic.

Answer 1

Slightly different example but, I found that by referencing the parent container (using ElementName) in the binding you can get to it's DataContext and its subsequent properties using the Path syntax. As shown below:

<ItemsControl x:Name="lstDevices" ItemsSource="{Binding DeviceMappings}">
 <ItemsControl.ItemTemplate>
  <DataTemplate>
   <Grid>
    <ComboBox Text="{Binding Device}" ItemsSource="{Binding ElementName=lstDevices, Path=DataContext.AvailableDevices}" />
    ...
   </Grid>
  </DataTemplate>
 </ItemsControl.ItemTemplate>
</ItemsControl>