WPF DataGrid DataGridComboBoxColumn ItemsSource Referenced Off DataGrid.ItemsSource

Question

I have a DataGrid like below

<DataGrid ItemsSource="{Binding Collection}" AutoGenerateColumns="False" CanUserAddRows="False" CanUserDeleteRows="False">
     <DataGrid.Columns>
          <DataGridTextColumn Header="Col1" Binding="{Binding Col1}" IsReadOnly="True" />
          <DataGridComboBoxColumn Header="Col2" ItemsSource="{Binding Col2}" SelectedItemBinding="{Binding Selected}" />
     </DataGrid.Columns>
</DataGrid>

The values that end up in Col1 are actually Window.DataContext.Collection[index].Col1 , but WPF seems to be looking for Col2's ItemsSource at Window.DataContext.Col2 . The actual path I need is Window.DataConext.Collection[index].Col2

Please note the reference to index above is not to a static value but to the fact that each row gets a value from one of the collection items.

How do I accomplish this?

Answer 1

Try this:

<DataGridComboBoxColumn Header="Col2"  SelectedItemBinding="{Binding Selected}" 
                        ItemsSource="{Binding RelativeSource={RelativeSource FindAncestor, 
                                                                             AncestorType={x:Type Window}}, 
                                              Path=DataContext.Collection[index].Col2}" />

Poor formatting. (insert a number for index )